diff --git a/packages/rest/.eslintrc.json b/packages/rest/.eslintrc.json
index 99ef7cec8051..bf98d1b08630 100644
--- a/packages/rest/.eslintrc.json
+++ b/packages/rest/.eslintrc.json
@@ -1,3 +1,11 @@
 {
-	"extends": "../../.eslintrc.json"
+	"extends": "../../.eslintrc.json",
+	"rules": {
+		"n/prefer-global/url": 0,
+		"n/prefer-global/url-search-params": 0,
+		"n/prefer-global/buffer": 0,
+		"n/prefer-global/process": 0,
+		"no-restricted-globals": 0,
+		"unicorn/prefer-node-protocol": 0
+	}
 }
diff --git a/packages/rest/.lintstagedrc.js b/packages/rest/.lintstagedrc.js
index dc17706a55ac..688ec53c18a3 100644
--- a/packages/rest/.lintstagedrc.js
+++ b/packages/rest/.lintstagedrc.js
@@ -1 +1,4 @@
-module.exports = require('../../.lintstagedrc.json');
+module.exports = {
+	...require('../../.lintstagedrc.json'),
+	'src/**.ts': 'vitest related --run --config ./vitest.config.ts',
+};
diff --git a/packages/rest/__tests__/setup.ts b/packages/rest/__tests__/setup.ts
new file mode 100644
index 000000000000..6d348870e67f
--- /dev/null
+++ b/packages/rest/__tests__/setup.ts
@@ -0,0 +1,4 @@
+import { setDefaultStrategy } from '../src/environment.js';
+import { makeRequest } from '../src/strategies/undiciRequest.js';
+
+setDefaultStrategy(makeRequest);
diff --git a/packages/rest/package.json b/packages/rest/package.json
index 041b68664318..cacbe3075484 100644
--- a/packages/rest/package.json
+++ b/packages/rest/package.json
@@ -14,14 +14,19 @@
 		"changelog": "git cliff --prepend ./CHANGELOG.md -u -c ./cliff.toml -r ../../ --include-path 'packages/rest/*'",
 		"release": "cliff-jumper"
 	},
-	"main": "./dist/index.js",
-	"module": "./dist/index.mjs",
-	"typings": "./dist/index.d.ts",
+	"types": "./dist/index.d.ts",
 	"exports": {
 		".": {
-			"types": "./dist/index.d.ts",
-			"import": "./dist/index.mjs",
-			"require": "./dist/index.js"
+			"node": {
+				"types": "./dist/index.d.ts",
+				"import": "./dist/index.mjs",
+				"require": "./dist/index.js"
+			},
+			"default": {
+				"types": "./dist/web.d.ts",
+				"import": "./dist/web.mjs",
+				"require": "./dist/web.js"
+			}
 		},
 		"./*": {
 			"types": "./dist/strategies/*.d.ts",
@@ -65,8 +70,9 @@
 		"@discordjs/util": "workspace:^",
 		"@sapphire/async-queue": "^1.5.0",
 		"@sapphire/snowflake": "^3.5.1",
+		"@vladfrangu/async_event_emitter": "^2.2.2",
 		"discord-api-types": "^0.37.45",
-		"file-type": "^18.4.0",
+		"magic-bytes.js": "^1.0.14",
 		"tslib": "^2.5.2",
 		"undici": "^5.22.1"
 	},
diff --git a/packages/rest/src/environment.ts b/packages/rest/src/environment.ts
new file mode 100644
index 000000000000..f59a1ce45ad9
--- /dev/null
+++ b/packages/rest/src/environment.ts
@@ -0,0 +1,11 @@
+import type { RESTOptions } from './shared.js';
+
+let defaultStrategy: RESTOptions['makeRequest'];
+
+export function setDefaultStrategy(newStrategy: RESTOptions['makeRequest']) {
+	defaultStrategy = newStrategy;
+}
+
+export function getDefaultStrategy() {
+	return defaultStrategy;
+}
diff --git a/packages/rest/src/index.ts b/packages/rest/src/index.ts
index b6af7b7ef7df..32934acf5466 100644
--- a/packages/rest/src/index.ts
+++ b/packages/rest/src/index.ts
@@ -1,15 +1,7 @@
-export * from './lib/CDN.js';
-export * from './lib/errors/DiscordAPIError.js';
-export * from './lib/errors/HTTPError.js';
-export * from './lib/errors/RateLimitError.js';
-export * from './lib/RequestManager.js';
-export * from './lib/REST.js';
-export * from './lib/utils/constants.js';
-export { calculateUserDefaultAvatarIndex, makeURLSearchParams, parseResponse } from './lib/utils/utils.js';
+import { shouldUseGlobalFetchAndWebSocket } from '@discordjs/util';
+import { setDefaultStrategy } from './environment.js';
+import { makeRequest } from './strategies/undiciRequest.js';
 
-/**
- * The {@link https://github.com/discordjs/discord.js/blob/main/packages/rest/#readme | @discordjs/rest} version
- * that you are currently using.
- */
-// This needs to explicitly be `string` so it is not typed as a "const string" that gets injected by esbuild
-export const version = '[VI]{{inject}}[/VI]' as string;
+setDefaultStrategy(shouldUseGlobalFetchAndWebSocket() ? fetch : makeRequest);
+
+export * from './shared.js';
diff --git a/packages/rest/src/lib/CDN.ts b/packages/rest/src/lib/CDN.ts
index a42966bd8829..38313f839a32 100644
--- a/packages/rest/src/lib/CDN.ts
+++ b/packages/rest/src/lib/CDN.ts
@@ -1,6 +1,4 @@
 /* eslint-disable jsdoc/check-param-names */
-
-import { URL } from 'node:url';
 import {
 	ALLOWED_EXTENSIONS,
 	ALLOWED_SIZES,
diff --git a/packages/rest/src/lib/REST.ts b/packages/rest/src/lib/REST.ts
index 4b24ab208639..03723d3017fe 100644
--- a/packages/rest/src/lib/REST.ts
+++ b/packages/rest/src/lib/REST.ts
@@ -1,7 +1,7 @@
-import { EventEmitter } from 'node:events';
 import type { Readable } from 'node:stream';
 import type { ReadableStream } from 'node:stream/web';
 import type { Collection } from '@discordjs/collection';
+import { AsyncEventEmitter } from '@vladfrangu/async_event_emitter';
 import type { Dispatcher, RequestInit, Response } from 'undici';
 import { CDN } from './CDN.js';
 import {
@@ -204,7 +204,7 @@ export interface APIRequest {
 }
 
 export interface ResponseLike
-	extends Pick<Response, 'arrayBuffer' | 'bodyUsed' | 'headers' | 'json' | 'ok' | 'status' | 'text'> {
+	extends Pick<Response, 'arrayBuffer' | 'bodyUsed' | 'headers' | 'json' | 'ok' | 'status' | 'statusText' | 'text'> {
 	body: Readable | ReadableStream | null;
 }
 
@@ -223,31 +223,16 @@ export interface RestEvents {
 	handlerSweep: [sweptHandlers: Collection<string, IHandler>];
 	hashSweep: [sweptHashes: Collection<string, HashData>];
 	invalidRequestWarning: [invalidRequestInfo: InvalidRequestWarningData];
-	newListener: [name: string, listener: (...args: any) => void];
 	rateLimited: [rateLimitInfo: RateLimitData];
-	removeListener: [name: string, listener: (...args: any) => void];
 	response: [request: APIRequest, response: ResponseLike];
 	restDebug: [info: string];
 }
 
-export interface REST {
-	emit: (<K extends keyof RestEvents>(event: K, ...args: RestEvents[K]) => boolean) &
-		(<S extends string | symbol>(event: Exclude<S, keyof RestEvents>, ...args: any[]) => boolean);
+export type RestEventsMap = {
+	[K in keyof RestEvents]: RestEvents[K];
+};
 
-	off: (<K extends keyof RestEvents>(event: K, listener: (...args: RestEvents[K]) => void) => this) &
-		(<S extends string | symbol>(event: Exclude<S, keyof RestEvents>, listener: (...args: any[]) => void) => this);
-
-	on: (<K extends keyof RestEvents>(event: K, listener: (...args: RestEvents[K]) => void) => this) &
-		(<S extends string | symbol>(event: Exclude<S, keyof RestEvents>, listener: (...args: any[]) => void) => this);
-
-	once: (<K extends keyof RestEvents>(event: K, listener: (...args: RestEvents[K]) => void) => this) &
-		(<S extends string | symbol>(event: Exclude<S, keyof RestEvents>, listener: (...args: any[]) => void) => this);
-
-	removeAllListeners: (<K extends keyof RestEvents>(event?: K) => this) &
-		(<S extends string | symbol>(event?: Exclude<S, keyof RestEvents>) => this);
-}
-
-export class REST extends EventEmitter {
+export class REST extends AsyncEventEmitter<RestEventsMap> {
 	public readonly cdn: CDN;
 
 	public readonly requestManager: RequestManager;
@@ -256,9 +241,13 @@ export class REST extends EventEmitter {
 		super();
 		this.cdn = new CDN(options.cdn ?? DefaultRestOptions.cdn);
 		this.requestManager = new RequestManager(options)
+			// @ts-expect-error For some reason ts can't infer these types
 			.on(RESTEvents.Debug, this.emit.bind(this, RESTEvents.Debug))
+			// @ts-expect-error For some reason ts can't infer these types
 			.on(RESTEvents.RateLimited, this.emit.bind(this, RESTEvents.RateLimited))
+			// @ts-expect-error For some reason ts can't infer these types
 			.on(RESTEvents.InvalidRequestWarning, this.emit.bind(this, RESTEvents.InvalidRequestWarning))
+			// @ts-expect-error For some reason ts can't infer these types
 			.on(RESTEvents.HashSweep, this.emit.bind(this, RESTEvents.HashSweep));
 
 		this.on('newListener', (name, listener) => {
diff --git a/packages/rest/src/lib/RequestManager.ts b/packages/rest/src/lib/RequestManager.ts
index 7b3abb8f6569..66920b03b668 100644
--- a/packages/rest/src/lib/RequestManager.ts
+++ b/packages/rest/src/lib/RequestManager.ts
@@ -1,12 +1,9 @@
-import { Blob, Buffer } from 'node:buffer';
-import { EventEmitter } from 'node:events';
-import { setInterval, clearInterval } from 'node:timers';
-import type { URLSearchParams } from 'node:url';
 import { Collection } from '@discordjs/collection';
-import { lazy } from '@discordjs/util';
 import { DiscordSnowflake } from '@sapphire/snowflake';
+import { AsyncEventEmitter } from '@vladfrangu/async_event_emitter';
+import { filetypeinfo } from 'magic-bytes.js';
 import type { RequestInit, BodyInit, Dispatcher, Agent } from 'undici';
-import type { RESTOptions, ResponseLike, RestEvents } from './REST.js';
+import type { RESTOptions, ResponseLike, RestEventsMap } from './REST.js';
 import { BurstHandler } from './handlers/BurstHandler.js';
 import { SequentialHandler } from './handlers/SequentialHandler.js';
 import type { IHandler } from './interfaces/Handler.js';
@@ -17,9 +14,7 @@ import {
 	OverwrittenMimeTypes,
 	RESTEvents,
 } from './utils/constants.js';
-
-// Make this a lazy dynamic import as file-type is a pure ESM package
-const getFileType = lazy(async () => import('file-type'));
+import { isBufferLike } from './utils/utils.js';
 
 /**
  * Represents a file to be added to the request
@@ -32,7 +27,7 @@ export interface RawFile {
 	/**
 	 * The actual data for the file
 	 */
-	data: Buffer | boolean | number | string;
+	data: Buffer | Uint8Array | boolean | number | string;
 	/**
 	 * An explicit key to use for key of the formdata field for this file.
 	 * When not provided, the index of the file in the files array is used in the form `files[${index}]`.
@@ -162,27 +157,10 @@ export interface HashData {
 	value: string;
 }
 
-export interface RequestManager {
-	emit: (<K extends keyof RestEvents>(event: K, ...args: RestEvents[K]) => boolean) &
-		(<S extends string | symbol>(event: Exclude<S, keyof RestEvents>, ...args: any[]) => boolean);
-
-	off: (<K extends keyof RestEvents>(event: K, listener: (...args: RestEvents[K]) => void) => this) &
-		(<S extends string | symbol>(event: Exclude<S, keyof RestEvents>, listener: (...args: any[]) => void) => this);
-
-	on: (<K extends keyof RestEvents>(event: K, listener: (...args: RestEvents[K]) => void) => this) &
-		(<S extends string | symbol>(event: Exclude<S, keyof RestEvents>, listener: (...args: any[]) => void) => this);
-
-	once: (<K extends keyof RestEvents>(event: K, listener: (...args: RestEvents[K]) => void) => this) &
-		(<S extends string | symbol>(event: Exclude<S, keyof RestEvents>, listener: (...args: any[]) => void) => this);
-
-	removeAllListeners: (<K extends keyof RestEvents>(event?: K) => this) &
-		(<S extends string | symbol>(event?: Exclude<S, keyof RestEvents>) => this);
-}
-
 /**
  * Represents the class that manages handlers for endpoints
  */
-export class RequestManager extends EventEmitter {
+export class RequestManager extends AsyncEventEmitter<RestEventsMap> {
 	/**
 	 * The {@link https://undici.nodejs.org/#/docs/api/Agent | Agent} for all requests
 	 * performed by this manager.
@@ -216,9 +194,9 @@ export class RequestManager extends EventEmitter {
 
 	#token: string | null = null;
 
-	private hashTimer!: NodeJS.Timer;
+	private hashTimer!: NodeJS.Timer | number;
 
-	private handlerTimer!: NodeJS.Timer;
+	private handlerTimer!: NodeJS.Timer | number;
 
 	public readonly options: RESTOptions;
 
@@ -269,7 +247,9 @@ export class RequestManager extends EventEmitter {
 
 				// Fire event
 				this.emit(RESTEvents.HashSweep, sweptHashes);
-			}, this.options.hashSweepInterval).unref();
+			}, this.options.hashSweepInterval);
+
+			this.hashTimer.unref?.();
 		}
 
 		if (this.options.handlerSweepInterval !== 0 && this.options.handlerSweepInterval !== Number.POSITIVE_INFINITY) {
@@ -292,7 +272,9 @@ export class RequestManager extends EventEmitter {
 
 				// Fire event
 				this.emit(RESTEvents.HandlerSweep, sweptHandlers);
-			}, this.options.handlerSweepInterval).unref();
+			}, this.options.handlerSweepInterval);
+
+			this.handlerTimer.unref?.();
 		}
 	}
 
@@ -425,14 +407,18 @@ export class RequestManager extends EventEmitter {
 				// FormData.append only accepts a string or Blob.
 				// https://developer.mozilla.org/en-US/docs/Web/API/Blob/Blob#parameters
 				// The Blob constructor accepts TypedArray/ArrayBuffer, strings, and Blobs.
-				if (Buffer.isBuffer(file.data)) {
+				if (isBufferLike(file.data)) {
 					// Try to infer the content type from the buffer if one isn't passed
-					const { fileTypeFromBuffer } = await getFileType();
 					let contentType = file.contentType;
+
 					if (!contentType) {
-						const parsedType = (await fileTypeFromBuffer(file.data))?.mime;
+						const [parsedType] = filetypeinfo(file.data);
+
 						if (parsedType) {
-							contentType = OverwrittenMimeTypes[parsedType as keyof typeof OverwrittenMimeTypes] ?? parsedType;
+							contentType =
+								OverwrittenMimeTypes[parsedType.mime as keyof typeof OverwrittenMimeTypes] ??
+								parsedType.mime ??
+								'application/octet-stream';
 						}
 					}
 
diff --git a/packages/rest/src/lib/errors/HTTPError.ts b/packages/rest/src/lib/errors/HTTPError.ts
index d9859e9400e8..f04982422c89 100644
--- a/packages/rest/src/lib/errors/HTTPError.ts
+++ b/packages/rest/src/lib/errors/HTTPError.ts
@@ -1,4 +1,3 @@
-import { STATUS_CODES } from 'node:http';
 import type { InternalRequest } from '../RequestManager.js';
 import type { RequestBody } from './DiscordAPIError.js';
 
@@ -12,18 +11,19 @@ export class HTTPError extends Error {
 
 	/**
 	 * @param status - The status code of the response
+	 * @param statusText - The status text of the response
 	 * @param method - The method of the request that erred
 	 * @param url - The url of the request that erred
 	 * @param bodyData - The unparsed data for the request that errored
 	 */
 	public constructor(
 		public status: number,
+		statusText: string,
 		public method: string,
 		public url: string,
 		bodyData: Pick<InternalRequest, 'body' | 'files'>,
 	) {
-		super(STATUS_CODES[status]);
-
+		super(statusText);
 		this.requestBody = { files: bodyData.files, json: bodyData.body };
 	}
 }
diff --git a/packages/rest/src/lib/handlers/BurstHandler.ts b/packages/rest/src/lib/handlers/BurstHandler.ts
index 971ac32d60a6..812abdde1ce0 100644
--- a/packages/rest/src/lib/handlers/BurstHandler.ts
+++ b/packages/rest/src/lib/handlers/BurstHandler.ts
@@ -1,10 +1,9 @@
-import { setTimeout as sleep } from 'node:timers/promises';
 import type { RequestInit } from 'undici';
 import type { ResponseLike } from '../REST.js';
 import type { HandlerRequestData, RequestManager, RouteData } from '../RequestManager.js';
 import type { IHandler } from '../interfaces/Handler.js';
 import { RESTEvents } from '../utils/constants.js';
-import { onRateLimit } from '../utils/utils.js';
+import { onRateLimit, sleep } from '../utils/utils.js';
 import { handleErrors, incrementInvalidCount, makeNetworkRequest } from './Shared.js';
 
 /**
diff --git a/packages/rest/src/lib/handlers/SequentialHandler.ts b/packages/rest/src/lib/handlers/SequentialHandler.ts
index f18919b18fe9..acfcc7072bfe 100644
--- a/packages/rest/src/lib/handlers/SequentialHandler.ts
+++ b/packages/rest/src/lib/handlers/SequentialHandler.ts
@@ -1,11 +1,10 @@
-import { setTimeout as sleep } from 'node:timers/promises';
 import { AsyncQueue } from '@sapphire/async-queue';
 import type { RequestInit } from 'undici';
 import type { RateLimitData, ResponseLike } from '../REST.js';
 import type { HandlerRequestData, RequestManager, RouteData } from '../RequestManager.js';
 import type { IHandler } from '../interfaces/Handler.js';
 import { RESTEvents } from '../utils/constants.js';
-import { hasSublimit, onRateLimit } from '../utils/utils.js';
+import { hasSublimit, onRateLimit, sleep } from '../utils/utils.js';
 import { handleErrors, incrementInvalidCount, makeNetworkRequest } from './Shared.js';
 
 const enum QueueType {
diff --git a/packages/rest/src/lib/handlers/Shared.ts b/packages/rest/src/lib/handlers/Shared.ts
index 42c3278b4bb0..b51c11202b17 100644
--- a/packages/rest/src/lib/handlers/Shared.ts
+++ b/packages/rest/src/lib/handlers/Shared.ts
@@ -1,5 +1,3 @@
-import { setTimeout, clearTimeout } from 'node:timers';
-import { Response } from 'undici';
 import type { RequestInit } from 'undici';
 import type { ResponseLike } from '../REST.js';
 import type { HandlerRequestData, RequestManager, RouteData } from '../RequestManager.js';
@@ -65,7 +63,7 @@ export async function makeNetworkRequest(
 	retries: number,
 ) {
 	const controller = new AbortController();
-	const timeout = setTimeout(() => controller.abort(), manager.options.timeout).unref();
+	const timeout = setTimeout(() => controller.abort(), manager.options.timeout);
 	if (requestData.signal) {
 		// If the user signal was aborted, abort the controller, else abort the local signal.
 		// The reason why we don't re-use the user's signal, is because users may use the same signal for multiple
@@ -135,7 +133,7 @@ export async function handleErrors(
 		}
 
 		// We are out of retries, throw an error
-		throw new HTTPError(status, method, url, requestData);
+		throw new HTTPError(status, res.statusText, method, url, requestData);
 	} else {
 		// Handle possible malformed requests
 		if (status >= 400 && status < 500) {
diff --git a/packages/rest/src/lib/utils/constants.ts b/packages/rest/src/lib/utils/constants.ts
index 98f84ac9d4fd..27d15cdc51ef 100644
--- a/packages/rest/src/lib/utils/constants.ts
+++ b/packages/rest/src/lib/utils/constants.ts
@@ -1,11 +1,7 @@
-import process from 'node:process';
-import { lazy } from '@discordjs/util';
+import { getUserAgentAppendix } from '@discordjs/util';
 import { APIVersion } from 'discord-api-types/v10';
-import type { RESTOptions } from '../REST.js';
-
-const getUndiciRequest = lazy(async () => {
-	return import('../../strategies/undiciRequest.js');
-});
+import { getDefaultStrategy } from '../../environment.js';
+import type { RESTOptions, ResponseLike } from '../REST.js';
 
 export const DefaultUserAgent =
 	`DiscordBot (https://discord.js.org, [VI]{{inject}}[/VI])` as `DiscordBot (https://discord.js.org, ${string})`;
@@ -13,7 +9,7 @@ export const DefaultUserAgent =
 /**
  * The default string to append onto the user agent.
  */
-export const DefaultUserAgentAppendix = process.release?.name === 'node' ? `Node.js/${process.version}` : '';
+export const DefaultUserAgentAppendix = getUserAgentAppendix();
 
 export const DefaultRestOptions = {
 	agent: null,
@@ -32,9 +28,8 @@ export const DefaultRestOptions = {
 	hashSweepInterval: 14_400_000, // 4 Hours
 	hashLifetime: 86_400_000, // 24 Hours
 	handlerSweepInterval: 3_600_000, // 1 Hour
-	async makeRequest(...args) {
-		const strategy = await getUndiciRequest();
-		return strategy.makeRequest(...args);
+	async makeRequest(...args): Promise<ResponseLike> {
+		return getDefaultStrategy()(...args);
 	},
 } as const satisfies Required<RESTOptions>;
 
diff --git a/packages/rest/src/lib/utils/utils.ts b/packages/rest/src/lib/utils/utils.ts
index 07d63e542d86..d7710a8ad96b 100644
--- a/packages/rest/src/lib/utils/utils.ts
+++ b/packages/rest/src/lib/utils/utils.ts
@@ -1,4 +1,3 @@
-import { URLSearchParams } from 'node:url';
 import type { RESTPatchAPIChannelJSONBody, Snowflake } from 'discord-api-types/v10';
 import type { RateLimitData, ResponseLike } from '../REST.js';
 import { type RequestManager, RequestMethod } from '../RequestManager.js';
@@ -121,3 +120,23 @@ export async function onRateLimit(manager: RequestManager, rateLimitData: RateLi
 export function calculateUserDefaultAvatarIndex(userId: Snowflake) {
 	return Number(BigInt(userId) >> 22n) % 6;
 }
+
+/**
+ * Sleeps for a given amount of time.
+ *
+ * @param ms - The amount of time (in milliseconds) to sleep for
+ */
+export async function sleep(ms: number): Promise<void> {
+	return new Promise<void>((resolve) => {
+		setTimeout(() => resolve(), ms);
+	});
+}
+
+/**
+ * Verifies that a value is a buffer-like object.
+ *
+ * @param value - The value to check
+ */
+export function isBufferLike(value: unknown): value is ArrayBuffer | Buffer | Uint8Array | Uint8ClampedArray {
+	return value instanceof ArrayBuffer || value instanceof Uint8Array || value instanceof Uint8ClampedArray;
+}
diff --git a/packages/rest/src/shared.ts b/packages/rest/src/shared.ts
new file mode 100644
index 000000000000..b6af7b7ef7df
--- /dev/null
+++ b/packages/rest/src/shared.ts
@@ -0,0 +1,15 @@
+export * from './lib/CDN.js';
+export * from './lib/errors/DiscordAPIError.js';
+export * from './lib/errors/HTTPError.js';
+export * from './lib/errors/RateLimitError.js';
+export * from './lib/RequestManager.js';
+export * from './lib/REST.js';
+export * from './lib/utils/constants.js';
+export { calculateUserDefaultAvatarIndex, makeURLSearchParams, parseResponse } from './lib/utils/utils.js';
+
+/**
+ * The {@link https://github.com/discordjs/discord.js/blob/main/packages/rest/#readme | @discordjs/rest} version
+ * that you are currently using.
+ */
+// This needs to explicitly be `string` so it is not typed as a "const string" that gets injected by esbuild
+export const version = '[VI]{{inject}}[/VI]' as string;
diff --git a/packages/rest/src/strategies/undiciRequest.ts b/packages/rest/src/strategies/undiciRequest.ts
index 691ab365f268..aba78514d68d 100644
--- a/packages/rest/src/strategies/undiciRequest.ts
+++ b/packages/rest/src/strategies/undiciRequest.ts
@@ -1,8 +1,8 @@
-import { Buffer } from 'node:buffer';
+import { STATUS_CODES } from 'node:http';
 import { URLSearchParams } from 'node:url';
 import { types } from 'node:util';
 import { type RequestInit, request } from 'undici';
-import type { ResponseLike } from '../index.js';
+import type { ResponseLike } from '../shared.js';
 
 export type RequestOptions = Exclude<Parameters<typeof request>[1], undefined>;
 
@@ -30,6 +30,7 @@ export async function makeRequest(url: string, init: RequestInit): Promise<Respo
 		},
 		headers: new Headers(res.headers as Record<string, string[] | string>),
 		status: res.statusCode,
+		statusText: STATUS_CODES[res.statusCode]!,
 		ok: res.statusCode >= 200 && res.statusCode < 300,
 	};
 }
diff --git a/packages/rest/src/web.ts b/packages/rest/src/web.ts
new file mode 100644
index 000000000000..71b466dd74d7
--- /dev/null
+++ b/packages/rest/src/web.ts
@@ -0,0 +1,5 @@
+import { setDefaultStrategy } from './environment.js';
+
+setDefaultStrategy(fetch);
+
+export * from './shared.js';
diff --git a/packages/rest/tsup.config.ts b/packages/rest/tsup.config.ts
index 10ddbde0c605..ebed6ffa4b05 100644
--- a/packages/rest/tsup.config.ts
+++ b/packages/rest/tsup.config.ts
@@ -2,6 +2,6 @@ import { esbuildPluginVersionInjector } from 'esbuild-plugin-version-injector';
 import { createTsupConfig } from '../../tsup.config.js';
 
 export default createTsupConfig({
-	entry: ['src/index.ts', 'src/strategies/*.ts'],
+	entry: ['src/index.ts', 'src/web.ts', 'src/strategies/*.ts'],
 	esbuildPlugins: [esbuildPluginVersionInjector()],
 });
diff --git a/packages/rest/vitest.config.ts b/packages/rest/vitest.config.ts
new file mode 100644
index 000000000000..87a74b225522
--- /dev/null
+++ b/packages/rest/vitest.config.ts
@@ -0,0 +1,11 @@
+import { defineProject, mergeConfig } from 'vitest/config';
+import configShared from '../../vitest.config.js';
+
+export default mergeConfig(
+	configShared,
+	defineProject({
+		test: {
+			setupFiles: ['./__tests__/setup.ts'],
+		},
+	}),
+);
diff --git a/packages/util/src/functions/index.ts b/packages/util/src/functions/index.ts
index f5fdc6654663..6010ae5544e8 100644
--- a/packages/util/src/functions/index.ts
+++ b/packages/util/src/functions/index.ts
@@ -1,3 +1,5 @@
 export * from './lazy.js';
 export * from './range.js';
 export * from './calculateShardId.js';
+export * from './runtime.js';
+export * from './userAgentAppendix.js';
diff --git a/packages/util/src/functions/runtime.ts b/packages/util/src/functions/runtime.ts
new file mode 100644
index 000000000000..60e82185c34f
--- /dev/null
+++ b/packages/util/src/functions/runtime.ts
@@ -0,0 +1,12 @@
+export function shouldUseGlobalFetchAndWebSocket() {
+	// Browser env and deno when ran directly
+	if (typeof globalThis.process === 'undefined') {
+		return 'fetch' in globalThis && 'WebSocket' in globalThis;
+	}
+
+	if ('versions' in globalThis.process) {
+		return 'deno' in globalThis.process.versions || 'bun' in globalThis.process.versions;
+	}
+
+	return false;
+}
diff --git a/packages/util/src/functions/userAgentAppendix.ts b/packages/util/src/functions/userAgentAppendix.ts
new file mode 100644
index 000000000000..95742aefa082
--- /dev/null
+++ b/packages/util/src/functions/userAgentAppendix.ts
@@ -0,0 +1,52 @@
+/* eslint-disable n/prefer-global/process */
+/* eslint-disable no-restricted-globals */
+
+/**
+ * Resolves the user agent appendix string for the current environment.
+ */
+export function getUserAgentAppendix(): string {
+	// https://vercel.com/docs/concepts/functions/edge-functions/edge-runtime#check-if-you're-running-on-the-edge-runtime
+	// @ts-expect-error Vercel Edge functions
+	if (typeof globalThis.EdgeRuntime !== 'undefined') {
+		return 'Vercel-Edge-Functions';
+	}
+
+	// @ts-expect-error Cloudflare Workers
+	if (typeof globalThis.R2 !== 'undefined' && typeof globalThis.WebSocketPair !== 'undefined') {
+		// https://developers.cloudflare.com/workers/runtime-apis/web-standards/#navigatoruseragent
+		return 'Cloudflare-Workers';
+	}
+
+	// https://docs.netlify.com/edge-functions/api/#netlify-global-object
+	// @ts-expect-error Netlify Edge functions
+	if (typeof globalThis.Netlify !== 'undefined') {
+		return 'Netlify-Edge-Functions';
+	}
+
+	// Most (if not all) edge environments will have `process` defined. Within a web browser we'll extract it using `navigator.userAgent`.
+	if (typeof globalThis.process !== 'object') {
+		// @ts-expect-error web env
+		if (typeof globalThis.navigator === 'object') {
+			// @ts-expect-error web env
+			return globalThis.navigator.userAgent;
+		}
+
+		return 'UnknownEnvironment';
+	}
+
+	if ('versions' in globalThis.process) {
+		if ('deno' in globalThis.process.versions) {
+			return `Deno/${globalThis.process.versions.deno}`;
+		}
+
+		if ('bun' in globalThis.process.versions) {
+			return `Bun/${globalThis.process.versions.bun}`;
+		}
+
+		if ('node' in globalThis.process.versions) {
+			return `Node.js/${globalThis.process.versions.node}`;
+		}
+	}
+
+	return 'UnknownEnvironment';
+}
diff --git a/packages/ws/src/ws/WebSocketShard.ts b/packages/ws/src/ws/WebSocketShard.ts
index 5671a69b28ff..04a2ffffd656 100644
--- a/packages/ws/src/ws/WebSocketShard.ts
+++ b/packages/ws/src/ws/WebSocketShard.ts
@@ -20,7 +20,7 @@ import {
 	type GatewayReceivePayload,
 	type GatewaySendPayload,
 } from 'discord-api-types/v10';
-import { WebSocket, type RawData } from 'ws';
+import { WebSocket, type Data } from 'ws';
 import type { Inflate } from 'zlib-sync';
 import type { IContextFetchingStrategy } from '../strategies/context/IContextFetchingStrategy.js';
 import { ImportantGatewayOpcodes, getInitialSendRateLimitState } from '../utils/constants.js';
@@ -80,6 +80,12 @@ export interface SendRateLimitState {
 	resetAt: number;
 }
 
+// TODO(vladfrangu): enable this once https://github.com/oven-sh/bun/issues/3392 is solved
+// const WebSocketConstructor: typeof WebSocket = shouldUseGlobalFetchAndWebSocket()
+// 	? (globalThis as any).WebSocket
+// 	: WebSocket;
+const WebSocketConstructor: typeof WebSocket = WebSocket;
+
 export class WebSocketShard extends AsyncEventEmitter<WebSocketShardEventsMap> {
 	private connection: WebSocket | null = null;
 
@@ -177,13 +183,27 @@ export class WebSocketShard extends AsyncEventEmitter<WebSocketShardEventsMap> {
 		const session = await this.strategy.retrieveSessionInfo(this.id);
 
 		const url = `${session?.resumeURL ?? this.strategy.options.gatewayInformation.url}?${params.toString()}`;
+
 		this.debug([`Connecting to ${url}`]);
-		const connection = new WebSocket(url, { handshakeTimeout: this.strategy.options.handshakeTimeout ?? undefined })
-			.on('message', this.onMessage.bind(this))
-			.on('error', this.onError.bind(this))
-			.on('close', this.onClose.bind(this));
+
+		const connection = new WebSocketConstructor(url, {
+			handshakeTimeout: this.strategy.options.handshakeTimeout ?? undefined,
+		});
 
 		connection.binaryType = 'arraybuffer';
+
+		connection.onmessage = (event) => {
+			void this.onMessage(event.data, event.data instanceof ArrayBuffer);
+		};
+
+		connection.onerror = (event) => {
+			this.onError(event.error);
+		};
+
+		connection.onclose = (event) => {
+			void this.onClose(event.code);
+		};
+
 		this.connection = connection;
 
 		this.#status = WebSocketShardStatus.Connecting;
@@ -247,9 +267,9 @@ export class WebSocketShard extends AsyncEventEmitter<WebSocketShardEventsMap> {
 
 		if (this.connection) {
 			// No longer need to listen to messages
-			this.connection.removeAllListeners('message');
+			this.connection.onmessage = null;
 			// Prevent a reconnection loop by unbinding the main close event
-			this.connection.removeAllListeners('close');
+			this.connection.onclose = null;
 
 			const shouldClose = this.connection.readyState === WebSocket.OPEN;
 
@@ -260,14 +280,22 @@ export class WebSocketShard extends AsyncEventEmitter<WebSocketShardEventsMap> {
 			]);
 
 			if (shouldClose) {
+				let outerResolve: () => void;
+				const promise = new Promise<void>((resolve) => {
+					outerResolve = resolve;
+				});
+
+				this.connection.onclose = outerResolve!;
+
 				this.connection.close(options.code, options.reason);
-				await once(this.connection, 'close');
+
+				await promise;
 				this.emit(WebSocketShardEvents.Closed, { code: options.code });
 			}
 
 			// Lastly, remove the error event.
 			// Doing this earlier would cause a hard crash in case an error event fired on our `close` call
-			this.connection.removeAllListeners('error');
+			this.connection.onerror = null;
 		} else {
 			this.debug(['Destroying a shard that has no connection; please open an issue on GitHub']);
 		}
@@ -461,17 +489,23 @@ export class WebSocketShard extends AsyncEventEmitter<WebSocketShardEventsMap> {
 		this.isAck = false;
 	}
 
-	private async unpackMessage(data: ArrayBuffer | Buffer, isBinary: boolean): Promise<GatewayReceivePayload | null> {
-		const decompressable = new Uint8Array(data);
-
+	private async unpackMessage(data: Data, isBinary: boolean): Promise<GatewayReceivePayload | null> {
 		// Deal with no compression
 		if (!isBinary) {
-			return JSON.parse(this.textDecoder.decode(decompressable)) as GatewayReceivePayload;
+			try {
+				return JSON.parse(data as string) as GatewayReceivePayload;
+			} catch {
+				// This is a non-JSON payload / (at the time of writing this comment) emitted by bun wrongly interpreting custom close codes https://github.com/oven-sh/bun/issues/3392
+				return null;
+			}
 		}
 
+		const decompressable = new Uint8Array(data as ArrayBuffer);
+
 		// Deal with identify compress
 		if (this.useIdentifyCompress) {
 			return new Promise((resolve, reject) => {
+				// eslint-disable-next-line promise/prefer-await-to-callbacks
 				inflate(decompressable, { chunkSize: 65_535 }, (err, result) => {
 					if (err) {
 						reject(err);
@@ -524,8 +558,8 @@ export class WebSocketShard extends AsyncEventEmitter<WebSocketShardEventsMap> {
 		return null;
 	}
 
-	private async onMessage(data: RawData, isBinary: boolean) {
-		const payload = await this.unpackMessage(data as ArrayBuffer | Buffer, isBinary);
+	private async onMessage(data: Data, isBinary: boolean) {
+		const payload = await this.unpackMessage(data, isBinary);
 		if (!payload) {
 			return;
 		}
diff --git a/yarn.lock b/yarn.lock
index e6fc8b6b4b62..b0ceffbaf40f 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -2318,13 +2318,14 @@ __metadata:
     "@sapphire/snowflake": ^3.5.1
     "@types/node": 18.16.14
     "@vitest/coverage-c8": ^0.31.1
+    "@vladfrangu/async_event_emitter": ^2.2.2
     cross-env: ^7.0.3
     discord-api-types: ^0.37.45
     esbuild-plugin-version-injector: ^1.1.0
     eslint: ^8.41.0
     eslint-config-neon: ^0.1.47
     eslint-formatter-pretty: ^5.0.0
-    file-type: ^18.4.0
+    magic-bytes.js: ^1.0.14
     prettier: ^2.8.8
     tslib: ^2.5.2
     tsup: ^6.7.0
@@ -6039,13 +6040,6 @@ __metadata:
   languageName: node
   linkType: hard
 
-"@tokenizer/token@npm:^0.3.0":
-  version: 0.3.0
-  resolution: "@tokenizer/token@npm:0.3.0"
-  checksum: 1d575d02d2a9f0c5a4ca5180635ebd2ad59e0f18b42a65f3d04844148b49b3db35cf00b6012a1af2d59c2ab3caca59451c5689f747ba8667ee586ad717ee58e1
-  languageName: node
-  linkType: hard
-
 "@tootallnate/once@npm:1":
   version: 1.1.2
   resolution: "@tootallnate/once@npm:1.1.2"
@@ -13528,17 +13522,6 @@ __metadata:
   languageName: node
   linkType: hard
 
-"file-type@npm:^18.4.0":
-  version: 18.4.0
-  resolution: "file-type@npm:18.4.0"
-  dependencies:
-    readable-web-to-node-stream: ^3.0.2
-    strtok3: ^7.0.0
-    token-types: ^5.0.1
-  checksum: 191aa44b662417d496efc51bfb061da4c51cddfe2e3f7467b580964c3d83dbd88f76662368ea231a84d489a7d8cfc0bc2df9fefc439b519c2e6ddc498122dae0
-  languageName: node
-  linkType: hard
-
 "file-uri-to-path@npm:1.0.0":
   version: 1.0.0
   resolution: "file-uri-to-path@npm:1.0.0"
@@ -15125,7 +15108,7 @@ __metadata:
   languageName: node
   linkType: hard
 
-"ieee754@npm:^1.1.13, ieee754@npm:^1.2.1":
+"ieee754@npm:^1.1.13":
   version: 1.2.1
   resolution: "ieee754@npm:1.2.1"
   checksum: 5144c0c9815e54ada181d80a0b810221a253562422e7c6c3a60b1901154184f49326ec239d618c416c1c5945a2e197107aee8d986a3dd836b53dffefd99b5e7e
@@ -17748,6 +17731,13 @@ __metadata:
   languageName: node
   linkType: hard
 
+"magic-bytes.js@npm:^1.0.14":
+  version: 1.0.14
+  resolution: "magic-bytes.js@npm:1.0.14"
+  checksum: 5431948f5134ea27134a2e9c197ce5fdc89677682d365f275b0193a816a037cb9fc1c5eeeb541920d653e3c44f9022d007ef4b159ec4f1a814945be9f6be8abc
+  languageName: node
+  linkType: hard
+
 "magic-string@npm:^0.27.0":
   version: 0.27.0
   resolution: "magic-string@npm:0.27.0"
@@ -20514,13 +20504,6 @@ __metadata:
   languageName: node
   linkType: hard
 
-"peek-readable@npm:^5.0.0":
-  version: 5.0.0
-  resolution: "peek-readable@npm:5.0.0"
-  checksum: bef5ceb50586eb42e14efba274ac57ffe97f0ed272df9239ce029f688f495d9bf74b2886fa27847c706a9db33acda4b7d23bbd09a2d21eb4c2a54da915117414
-  languageName: node
-  linkType: hard
-
 "peek-stream@npm:^1.1.0":
   version: 1.1.3
   resolution: "peek-stream@npm:1.1.3"
@@ -21707,15 +21690,6 @@ __metadata:
   languageName: node
   linkType: hard
 
-"readable-web-to-node-stream@npm:^3.0.2":
-  version: 3.0.2
-  resolution: "readable-web-to-node-stream@npm:3.0.2"
-  dependencies:
-    readable-stream: ^3.6.0
-  checksum: 8c56cc62c68513425ddfa721954875b382768f83fa20e6b31e365ee00cbe7a3d6296f66f7f1107b16cd3416d33aa9f1680475376400d62a081a88f81f0ea7f9c
-  languageName: node
-  linkType: hard
-
 "readdirp@npm:~3.6.0":
   version: 3.6.0
   resolution: "readdirp@npm:3.6.0"
@@ -23708,16 +23682,6 @@ __metadata:
   languageName: node
   linkType: hard
 
-"strtok3@npm:^7.0.0":
-  version: 7.0.0
-  resolution: "strtok3@npm:7.0.0"
-  dependencies:
-    "@tokenizer/token": ^0.3.0
-    peek-readable: ^5.0.0
-  checksum: 2ebe7ad8f2aea611dec6742cf6a42e82764892a362907f7ce493faf334501bf981ce21c828dcc300457e6d460dc9c34d644ededb3b01dcb9e37559203cf1748c
-  languageName: node
-  linkType: hard
-
 "style-loader@npm:^3.3.2":
   version: 3.3.3
   resolution: "style-loader@npm:3.3.3"
@@ -24259,16 +24223,6 @@ __metadata:
   languageName: node
   linkType: hard
 
-"token-types@npm:^5.0.1":
-  version: 5.0.1
-  resolution: "token-types@npm:5.0.1"
-  dependencies:
-    "@tokenizer/token": ^0.3.0
-    ieee754: ^1.2.1
-  checksum: 32780123bc6ce8b6a2231d860445c994a02a720abf38df5583ea957aa6626873cd1c4dd8af62314da4cf16ede00c379a765707a3b06f04b8808c38efdae1c785
-  languageName: node
-  linkType: hard
-
 "toml@npm:^3.0.0":
   version: 3.0.0
   resolution: "toml@npm:3.0.0"