diff --git a/packages/endo/bin/endo b/packages/endo/bin/endo
new file mode 120000
index 0000000000..8237050ebd
--- /dev/null
+++ b/packages/endo/bin/endo
@@ -0,0 +1 @@
+endo.js
\ No newline at end of file
diff --git a/packages/endo/bin/endo.js b/packages/endo/bin/endo.js
new file mode 100755
index 0000000000..da980e130d
--- /dev/null
+++ b/packages/endo/bin/endo.js
@@ -0,0 +1,5 @@
+#!/usr/bin/env node
+import fs from "fs";
+import { main } from "../src/cli.js";
+
+main(process, { fs: fs.promises });
diff --git a/packages/endo/package.json b/packages/endo/package.json
index 04ca0a83b3..8e8505343a 100644
--- a/packages/endo/package.json
+++ b/packages/endo/package.json
@@ -14,6 +14,9 @@
     "require": "./dist/endo.cjs",
     "browser": "./dist/endo.umd.js"
   },
+  "bin": {
+    "endo": "./bin/endo.js"
+  },
   "scripts": {
     "build": "rollup --config rollup.config.js",
     "clean": "rm -rf dist",
diff --git a/packages/endo/src/cli.js b/packages/endo/src/cli.js
new file mode 100644
index 0000000000..868546f3a2
--- /dev/null
+++ b/packages/endo/src/cli.js
@@ -0,0 +1,110 @@
+/* eslint no-shadow: [0] */
+import "./lockdown.js";
+import { writeArchive } from "./main.js";
+import { search } from "./search.js";
+import { compartmentMapForNodeModules } from "./compartmap.js";
+
+function usage(message) {
+  console.error(message);
+  return 1;
+}
+
+async function noEntryUsage() {
+  return usage(`expected path to program`);
+}
+
+async function noArchiveUsage() {
+  return usage(`expected path for archive`);
+}
+
+async function subcommand([arg, ...rest], handlers) {
+  const keys = Object.keys(handlers);
+  if (arg === undefined || !keys.includes(arg)) {
+    return usage(`expected one of ${keys.join(", ")}`);
+  }
+  return handlers[arg](rest);
+}
+
+async function parameter(args, handle, usage) {
+  const [arg, ...rest] = args;
+  if (arg === undefined) {
+    return usage(`expected an argument`);
+  }
+  if (arg.startsWith("-")) {
+    return usage(`unexpected flag: ${arg}`);
+  }
+  return handle(arg, rest);
+}
+
+async function run(args, { cwd, read, write, stdout }) {
+  async function compartmap(args) {
+    async function handleEntry(applicationPath, args) {
+      if (args.length) {
+        return usage(`unexpected arguments: ${JSON.stringify(args)}`);
+      }
+      const currentLocation = new URL(`${cwd()}/`, "file:///");
+      const applicationLocation = new URL(applicationPath, currentLocation);
+      const { packageLocation } = await search(read, applicationLocation);
+      const compartmentMap = await compartmentMapForNodeModules(
+        read,
+        packageLocation
+      );
+      stdout.write(`${JSON.stringify(compartmentMap, null, 2)}\n`);
+      return 0;
+    }
+    return parameter(args, handleEntry, noEntryUsage);
+  }
+
+  async function archive(args) {
+    async function handleArchive(archivePath, args) {
+      async function handleEntry(applicationPath, args) {
+        if (args.length) {
+          return usage(`unexpected arguments: ${JSON.stringify(args)}`);
+        }
+        const currentLocation = new URL(`${cwd()}/`, "file:///");
+        const archiveLocation = new URL(archivePath, currentLocation);
+        const applicationLocation = new URL(applicationPath, currentLocation);
+        await writeArchive(write, read, archiveLocation, applicationLocation);
+        return 0;
+      }
+      return parameter(args, handleEntry, noEntryUsage);
+    }
+    return parameter(args, handleArchive, noArchiveUsage);
+  }
+
+  return subcommand(args, { compartmap, archive });
+}
+
+export async function main(process, modules) {
+  const { fs } = modules;
+  const { cwd, stdout } = process;
+
+  // Filesystem errors often don't have stacks:
+
+  async function read(location) {
+    try {
+      return await fs.readFile(new URL(location).pathname);
+    } catch (error) {
+      throw new Error(error.message);
+    }
+  }
+
+  async function write(location, content) {
+    try {
+      return await fs.writeFile(new URL(location).pathname, content);
+    } catch (error) {
+      throw new Error(error.message);
+    }
+  }
+
+  try {
+    process.exitCode = await run(process.argv.slice(2), {
+      read,
+      write,
+      cwd,
+      stdout
+    });
+  } catch (error) {
+    process.exitCode = usage(error.stack || error.message);
+  }
+}
diff --git a/packages/endo/src/compartmap.js b/packages/endo/src/compartmap.js
index 01f435a175..6b5f9afc4f 100644
--- a/packages/endo/src/compartmap.js
+++ b/packages/endo/src/compartmap.js
@@ -102,7 +102,7 @@ const inferParsers = (type, location) => {
 // that the package exports.
 
 const graphPackage = async (
-  name,
+  name = "",
   readDescriptor,
   graph,
   { packageLocation, packageDescriptor },
diff --git a/packages/endo/src/import-archive.js b/packages/endo/src/import-archive.js
index bf3957c1fd..b6c9f501c8 100644
--- a/packages/endo/src/import-archive.js
+++ b/packages/endo/src/import-archive.js
@@ -22,8 +22,8 @@ const makeArchiveImportHookMaker = archive => {
   return makeImportHook;
 };
 
-export const parseArchive = async archiveBytes => {
-  const archive = await readZip(archiveBytes);
+export const parseArchive = async (archiveBytes, archiveLocation) => {
+  const archive = await readZip(archiveBytes, archiveLocation);
 
   const compartmentMapBytes = await archive.read("compartmap.json");
   const compartmentMapText = decoder.decode(compartmentMapBytes);
@@ -47,12 +47,17 @@ export const parseArchive = async archiveBytes => {
   return { execute };
 };
 
-export const loadArchive = async (read, archivePath) => {
-  const archiveBytes = await read(archivePath);
-  return parseArchive(archiveBytes);
+export const loadArchive = async (read, archiveLocation) => {
+  const archiveBytes = await read(archiveLocation);
+  return parseArchive(archiveBytes, archiveLocation);
 };
 
-export const importArchive = async (read, archivePath, endowments, modules) => {
-  const archive = await loadArchive(read, archivePath);
+export const importArchive = async (
+  read,
+  archiveLocation,
+  endowments,
+  modules
+) => {
+  const archive = await loadArchive(read, archiveLocation);
   return archive.execute(endowments, modules);
 };
diff --git a/packages/endo/src/zip.js b/packages/endo/src/zip.js
index fddc3cc275..022e8d23f5 100644
--- a/packages/endo/src/zip.js
+++ b/packages/endo/src/zip.js
@@ -2,10 +2,18 @@
 
 import JSZip from "jszip";
 
-export const readZip = async data => {
+export const readZip = async (data, location) => {
   const zip = new JSZip();
   await zip.loadAsync(data);
-  const read = async path => zip.file(path).async("uint8array");
+  const read = async path => {
+    const file = zip.file(path);
+    if (file === undefined) {
+      throw new Error(
+        `Cannot find file to read ${path} in archive ${location}`
+      );
+    }
+    return file.async("uint8array");
+  };
   return { read };
 };