diff --git a/examples/arithmetics/example/example.calc b/examples/arithmetics/example/example.calc
index 595e5f954..5bbfa86f3 100644
--- a/examples/arithmetics/example/example.calc
+++ b/examples/arithmetics/example/example.calc
@@ -1,14 +1,14 @@
-module example1
+Module example1
 
-def y: 1 + 3 - 99828932 / 2 + 2 - 1;
+Def y: 1 + 3 - 99828932 / 2 + 2 - 1;
 
-def x: 12 / 3 - 1;
+DEF x: 12 / 3 - 1;
 
 x * 2 - 4;
 
 def t: 4;
 
-def func(t, x):
+DEF func(t, x):
     t * t * t + x;
 
 func(t, x);
diff --git a/examples/arithmetics/langium-config.json b/examples/arithmetics/langium-config.json
index 4439b7a7d..4603058ec 100644
--- a/examples/arithmetics/langium-config.json
+++ b/examples/arithmetics/langium-config.json
@@ -4,6 +4,7 @@
         "id": "arithmetics",
         "grammar": "src/language-server/arithmetics.langium",
         "fileExtensions": [".calc"],
+        "caseInsensitive": true,
         "textMate": {
             "out": "syntaxes/arithmetics.tmLanguage.json"
         }
diff --git a/examples/arithmetics/src/language-server/generated/module.ts b/examples/arithmetics/src/language-server/generated/module.ts
index ac2714d3e..5c3ac3367 100644
--- a/examples/arithmetics/src/language-server/generated/module.ts
+++ b/examples/arithmetics/src/language-server/generated/module.ts
@@ -9,7 +9,8 @@ import { ArithmeticsGrammar } from './grammar';
 
 export const ArithmeticsLanguageMetaData: LanguageMetaData = {
     languageId: 'arithmetics',
-    fileExtensions: ['.calc']
+    fileExtensions: ['.calc'],
+    caseInsensitive: true
 };
 
 export const ArithmeticsGeneratedSharedModule: Module<LangiumSharedServices, LangiumGeneratedSharedServices> = {
diff --git a/examples/arithmetics/syntaxes/arithmetics.tmLanguage.json b/examples/arithmetics/syntaxes/arithmetics.tmLanguage.json
index cdcd6f4dd..21f6ca2fc 100644
--- a/examples/arithmetics/syntaxes/arithmetics.tmLanguage.json
+++ b/examples/arithmetics/syntaxes/arithmetics.tmLanguage.json
@@ -10,7 +10,7 @@
     },
     {
       "name": "keyword.control.arithmetics",
-      "match": "\\b(def|module)\\b"
+      "match": "\\b([dD][eE][fF]|[mM][oO][dD][uU][lL][eE])\\b"
     }
   ],
   "repository": {
diff --git a/examples/domainmodel/src/language-server/generated/module.ts b/examples/domainmodel/src/language-server/generated/module.ts
index aa93e79dc..f9f7ad32b 100644
--- a/examples/domainmodel/src/language-server/generated/module.ts
+++ b/examples/domainmodel/src/language-server/generated/module.ts
@@ -9,7 +9,8 @@ import { DomainModelGrammar } from './grammar';
 
 export const DomainModelLanguageMetaData: LanguageMetaData = {
     languageId: 'domain-model',
-    fileExtensions: ['.dmodel']
+    fileExtensions: ['.dmodel'],
+    caseInsensitive: false
 };
 
 export const parserConfig: IParserConfig = {
diff --git a/examples/statemachine/src/language-server/generated/module.ts b/examples/statemachine/src/language-server/generated/module.ts
index 7bb5804a6..04dde94cd 100644
--- a/examples/statemachine/src/language-server/generated/module.ts
+++ b/examples/statemachine/src/language-server/generated/module.ts
@@ -9,7 +9,8 @@ import { StatemachineGrammar } from './grammar';
 
 export const StatemachineLanguageMetaData: LanguageMetaData = {
     languageId: 'statemachine',
-    fileExtensions: ['.statemachine']
+    fileExtensions: ['.statemachine'],
+    caseInsensitive: false
 };
 
 export const StatemachineGeneratedSharedModule: Module<LangiumSharedServices, LangiumGeneratedSharedServices> = {
diff --git a/packages/langium-cli/langium-config-schema.json b/packages/langium-cli/langium-config-schema.json
index d42bbb1b7..f8cb5d138 100644
--- a/packages/langium-cli/langium-config-schema.json
+++ b/packages/langium-cli/langium-config-schema.json
@@ -69,6 +69,10 @@
                                 }
                             ]
                         },
+                        "caseInsensitive": {
+                            "description": "Enable case-insensitive keywords parsing",
+                            "type": "boolean"
+                        },        
                         "textMate": {
                             "description": "An object to describe the textMate grammar properties",
                             "type": "object",
diff --git a/packages/langium-cli/src/generator/module-generator.ts b/packages/langium-cli/src/generator/module-generator.ts
index 36dcd8006..df4d52724 100644
--- a/packages/langium-cli/src/generator/module-generator.ts
+++ b/packages/langium-cli/src/generator/module-generator.ts
@@ -40,7 +40,8 @@ export function generateModule(grammars: langium.Grammar[], config: LangiumConfi
         node.append('export const ', grammar.name, 'LanguageMetaData: LanguageMetaData = {', NL);
         node.indent(metaData => {
             metaData.append(`languageId: '${config.id}',`, NL);
-            metaData.append(`fileExtensions: [${config.fileExtensions && config.fileExtensions.map(e => appendQuotesAndDot(e)).join(', ')}]`, NL);
+            metaData.append(`fileExtensions: [${config.fileExtensions && config.fileExtensions.map(e => appendQuotesAndDot(e)).join(', ')}],`, NL);
+            metaData.append(`caseInsensitive: ${!!config.caseInsensitive}`, NL);
         });
         node.append('};', NL, NL);
     }
diff --git a/packages/langium-cli/src/generator/textmate-generator.ts b/packages/langium-cli/src/generator/textmate-generator.ts
index 0643c3e96..93685d964 100644
--- a/packages/langium-cli/src/generator/textmate-generator.ts
+++ b/packages/langium-cli/src/generator/textmate-generator.ts
@@ -5,7 +5,7 @@
  ******************************************************************************/
 
 import * as langium from 'langium';
-import { escapeRegExp, getTerminalParts, isCommentTerminal, isTerminalRule, terminalRegex } from 'langium';
+import { escapeRegExp, getCaseInsensitivePattern, getTerminalParts, isCommentTerminal, isTerminalRule, terminalRegex } from 'langium';
 import { LangiumLanguageConfig } from '../package';
 import { collectKeywords } from './util';
 
@@ -117,15 +117,14 @@ function getRepository(grammar: langium.Grammar, config: LangiumLanguageConfig):
 function getControlKeywords(grammar: langium.Grammar, pack: LangiumLanguageConfig): Pattern {
     const regex = /[A-Za-z]/;
     const controlKeywords = collectKeywords(grammar).filter(kw => regex.test(kw));
-    const keywords = controlKeywords.map(escapeRegExp);
-    const groups = groupKeywords(keywords);
+    const groups = groupKeywords(controlKeywords, pack.caseInsensitive);
     return {
         'name': `keyword.control.${pack.id}`,
         'match': groups.join('|')
     };
 }
 
-function groupKeywords(keywords: string[]): string[] {
+function groupKeywords(keywords: string[], caseInsensitive: boolean | undefined): string[] {
     const groups: {
         letter: string[],
         leftSpecial: string[],
@@ -134,17 +133,18 @@ function groupKeywords(keywords: string[]): string[] {
     } = {letter: [], leftSpecial: [], rightSpecial: [], special: []};
 
     keywords.forEach(keyword => {
+        const keywordPattern = caseInsensitive ? getCaseInsensitivePattern(keyword) : escapeRegExp(keyword);
         if (/\w/.test(keyword[0])) {
             if (/\w/.test(keyword[keyword.length - 1])) {
-                groups.letter.push(keyword);
+                groups.letter.push(keywordPattern);
             } else {
-                groups.rightSpecial.push(keyword);
+                groups.rightSpecial.push(keywordPattern);
             }
         } else {
             if ((/\w/).test(keyword[keyword.length - 1])) {
-                groups.leftSpecial.push(keyword);
+                groups.leftSpecial.push(keywordPattern);
             } else {
-                groups.special.push(keyword);
+                groups.special.push(keywordPattern);
             }
         }
     });
diff --git a/packages/langium-cli/src/package.ts b/packages/langium-cli/src/package.ts
index 21502b32d..9fa80ff60 100644
--- a/packages/langium-cli/src/package.ts
+++ b/packages/langium-cli/src/package.ts
@@ -36,6 +36,8 @@ export interface LangiumLanguageConfig {
     grammar: string
     /** File extensions with leading `.` */
     fileExtensions?: string[]
+    /** Enable case-insensitive keywords parsing */
+    caseInsensitive?: boolean
     /** Enable generating a TextMate syntax highlighting file */
     textMate?: {
         /** Output path to syntax highlighting file */
diff --git a/packages/langium/src/grammar/generated/module.ts b/packages/langium/src/grammar/generated/module.ts
index 7d10660ca..7f997f77b 100644
--- a/packages/langium/src/grammar/generated/module.ts
+++ b/packages/langium/src/grammar/generated/module.ts
@@ -11,7 +11,8 @@ import { LangiumGrammarGrammar } from './grammar';
 
 export const LangiumGrammarLanguageMetaData: LanguageMetaData = {
     languageId: 'langium',
-    fileExtensions: ['.langium']
+    fileExtensions: ['.langium'],
+    caseInsensitive: false
 };
 
 export const LangiumGrammarGeneratedSharedModule: Module<LangiumSharedServices, LangiumGeneratedSharedServices> = {
diff --git a/packages/langium/src/grammar/language-meta-data.ts b/packages/langium/src/grammar/language-meta-data.ts
index a0e73f1c9..a43651c70 100644
--- a/packages/langium/src/grammar/language-meta-data.ts
+++ b/packages/langium/src/grammar/language-meta-data.ts
@@ -7,4 +7,5 @@
 export interface LanguageMetaData {
     languageId: string;
     fileExtensions: string[];
+    caseInsensitive: boolean;
 }
diff --git a/packages/langium/src/parser/langium-parser-builder.ts b/packages/langium/src/parser/langium-parser-builder.ts
index 49f5c5ecf..2a72d9360 100644
--- a/packages/langium/src/parser/langium-parser-builder.ts
+++ b/packages/langium/src/parser/langium-parser-builder.ts
@@ -31,7 +31,7 @@ type Method = () => void;
 export function createLangiumParser(services: LangiumServices): LangiumParser {
     const grammar = services.Grammar;
     const tokens = new Map<string, TokenType>();
-    const buildTokens = services.parser.TokenBuilder.buildTokens(grammar);
+    const buildTokens = services.parser.TokenBuilder.buildTokens(grammar, { caseInsensitive: services.LanguageMetaData.caseInsensitive });
     buildTokens.forEach(e => {
         tokens.set(e.name, e);
     });
diff --git a/packages/langium/src/parser/token-builder.ts b/packages/langium/src/parser/token-builder.ts
index f0848d291..c55564a6d 100644
--- a/packages/langium/src/parser/token-builder.ts
+++ b/packages/langium/src/parser/token-builder.ts
@@ -8,11 +8,11 @@ import { Lexer, TokenPattern, TokenType } from 'chevrotain';
 import { terminalRegex } from '..';
 import { Grammar, isKeyword, isTerminalRule, Keyword, TerminalRule } from '../grammar/generated/ast';
 import { streamAllContents } from '../utils/ast-util';
-import { partialMatches } from '../utils/regex-util';
+import { getCaseInsensitivePattern, partialMatches } from '../utils/regex-util';
 import { stream } from '../utils/stream';
 
 export interface TokenBuilder {
-    buildTokens(grammar: Grammar): TokenType[];
+    buildTokens(grammar: Grammar, options?: { caseInsensitive?: boolean }): TokenType[];
 }
 
 export class DefaultTokenBuilder implements TokenBuilder {
@@ -21,7 +21,7 @@ export class DefaultTokenBuilder implements TokenBuilder {
     protected readonly KEYWORD_SUFFIX = '_KEYWORD';
     protected readonly TERMINAL_SUFFIX = '_TERMINAL';
 
-    buildTokens(grammar: Grammar): TokenType[] {
+    buildTokens(grammar: Grammar, options?: { caseInsensitive?: boolean }): TokenType[] {
         const tokenMap = new Map<string, TokenType>();
         const terminalsTokens: TokenType[] = [];
         const terminals = Array.from(stream(grammar.rules).filter(isTerminalRule));
@@ -37,7 +37,7 @@ export class DefaultTokenBuilder implements TokenBuilder {
             .sort((a, b) => b.value.length - a.value.length);
 
         for (const keyword of keywords) {
-            const keywordToken = this.buildKeywordToken(keyword, keywords, terminals, tokenMap);
+            const keywordToken = this.buildKeywordToken(keyword, keywords, terminals, tokenMap, !!options?.caseInsensitive);
             tokens.push(keywordToken);
             tokenMap.set(keyword.value + this.KEYWORD_SUFFIX, keywordToken);
         }
@@ -74,13 +74,15 @@ export class DefaultTokenBuilder implements TokenBuilder {
         return token;
     }
 
-    protected buildKeywordToken(keyword: Keyword, keywords: Keyword[], terminals: TerminalRule[], tokenMap: Map<string, TokenType>): TokenType {
+    protected buildKeywordToken(keyword: Keyword, keywords: Keyword[], terminals: TerminalRule[], tokenMap: Map<string, TokenType>, caseInsensitive: boolean): TokenType {
         const longerAlt = this.findLongerAlt(keyword, keywords, terminals, tokenMap);
-        return { name: keyword.value, PATTERN: this.buildKeywordPattern(keyword), LONGER_ALT: longerAlt };
+        return { name: keyword.value, PATTERN: this.buildKeywordPattern(keyword, caseInsensitive), LONGER_ALT: longerAlt };
     }
 
-    protected buildKeywordPattern(keyword: Keyword): TokenPattern {
-        return keyword.value;
+    protected buildKeywordPattern(keyword: Keyword, caseInsensitive: boolean): TokenPattern {
+        return caseInsensitive ?
+            new RegExp(getCaseInsensitivePattern(keyword.value)) :
+            keyword.value;
     }
 
     protected findLongerAlt(keyword: Keyword, keywords: Keyword[], terminals: TerminalRule[], tokenMap: Map<string, TokenType>): TokenType[] {
diff --git a/packages/langium/src/utils/regex-util.ts b/packages/langium/src/utils/regex-util.ts
index 514a539b3..09e70a350 100644
--- a/packages/langium/src/utils/regex-util.ts
+++ b/packages/langium/src/utils/regex-util.ts
@@ -114,6 +114,12 @@ export function escapeRegExp(value: string): string {
     return value.replace(/[.*+?^${}()|[\]\\]/g, '\\$&');
 }
 
+export function getCaseInsensitivePattern(keyword: string): string {
+    return Array.prototype.map.call(keyword, letter =>
+        /\w/.test(letter) ? `[${letter.toLowerCase()}${letter.toUpperCase()}]` : escapeRegExp(letter)
+    ).join('');
+}
+
 /**
  * Determines whether the given input has a partial match with the specified regex.
  * @param regex The regex to partially match against
diff --git a/packages/langium/test/parser/token-builder.test.ts b/packages/langium/test/parser/token-builder.test.ts
index 42ecdf55e..553493fef 100644
--- a/packages/langium/test/parser/token-builder.test.ts
+++ b/packages/langium/test/parser/token-builder.test.ts
@@ -4,7 +4,7 @@
  * terms of the MIT License, which is available in the project root.
  ******************************************************************************/
 
-import { TokenType } from '@chevrotain/types';
+import { TokenPattern, TokenType } from '@chevrotain/types';
 import { createLangiumGrammarServices, Grammar } from '../../src';
 import { parseHelper } from '../../src/test';
 
@@ -53,3 +53,63 @@ describe('tokenBuilder#longerAlts', () => {
     });
 
 });
+
+let implementPattern: TokenPattern | undefined;
+let strangePattern: TokenPattern | undefined;
+let abcPattern: TokenPattern | undefined;
+let abPattern: TokenPattern | undefined;
+let aPattern: TokenPattern | undefined;
+let booleanTerminalPattern: TokenPattern | undefined;
+let abTerminalPattern: TokenPattern | undefined;
+
+describe('tokenBuilder#caseInsensitivePattern', () => {
+    beforeAll(async () => {
+        const text = `
+        grammar test
+        Main: 'A' 'ab' 'AbC' | Implement | '\\strange\\';
+        Implement: '@implement' AB;
+        terminal BOOLEAN returns boolean: /true|false/;
+        terminal AB: /ABD?/;
+        `;
+        const grammar = (await parseHelper<Grammar>(grammarServices)(text)).document.parseResult.value;
+        const tokens = tokenBuilder.buildTokens(grammar, { caseInsensitive: true });
+        const patterns = tokens.map(token => token.PATTERN);
+
+        implementPattern = patterns[0];
+        strangePattern = patterns[1];
+        abcPattern = patterns[2];
+        abPattern = patterns[3];
+        aPattern = patterns[4];
+        booleanTerminalPattern = patterns[5];
+        abTerminalPattern = patterns[6];
+    });
+
+    test('should create from keyword with special symbols', () => {
+        expect(implementPattern).toEqual(new RegExp(/@[iI][mM][pP][lL][eE][mM][eE][nN][tT]/));
+    });
+
+    test('should create from keyword with special escape symbols', () => {
+        expect(strangePattern).toEqual(new RegExp(/\\[sS][tT][rR][aA][nN][gG][eE]\\/));
+    });
+
+    test('should create from mixed-case word', () => {
+        expect(abcPattern).toEqual(new RegExp(/[aA][bB][cC]/));
+    });
+
+    test('should create from lower-case word', () => {
+        expect(abPattern).toEqual(new RegExp(/[aA][bB]/));
+    });
+
+    test('should create from upper-case word', () => {
+        expect(aPattern).toEqual(new RegExp(/[aA]/));
+    });
+
+    test('should ignore terminals', () => {
+        expect(booleanTerminalPattern).toEqual(new RegExp(/true|false/));
+    });
+
+    test('should ignore terminals with ?', () => {
+        expect(abTerminalPattern).toEqual(new RegExp(/ABD?/));
+    });
+
+});