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The same 55-language comment removal engine, available as a REST API, npm package, and CLI. Zero dependencies. Works everywhere.

The engine ships as the open-source uncommenter package on npm and powers the same browser tool you can use directly. The parser is character-driven so it understands the difference between a comment and comment-like syntax inside template literals, regex literals, and Python docstrings.

For deeper context on the design and trade-offs, see the about page or browse the engineering blog.

REST API

3 endpoints, JSON in/out, auto-detection

npm Package

Zero deps, CJS + ESM, full TypeScript

CLI

Files, dirs, stdin, diff, dry-run

REST API

Three endpoints. JSON in, JSON out. No API key required.

POST/api/v1/uncomment

Remove comments from source code. Supports all 55 languages with auto-detection.

Parameters

Name	Type	Required	Default	Description
code	string	Yes	—	Source code to process
language	string	No	—	Language ID (e.g. "python"). Omit for auto-detection.
filename	string	No	—	Filename for extension-based detection
options.preserveDocstrings	boolean	No	true	Keep docstrings (Python, Elixir)
options.preserveShebangs	boolean	No	true	Keep shebang lines (#!/...)
options.preserveTodos	boolean	No	false	Keep TODO/FIXME comments

Request

{
  "code": "def hello():\n    # comment\n    print('hi')",
  "language": "python",
  "options": {
    "preserveDocstrings": true,
    "preserveTodos": false
  }
}

Response

{
  "processed": "def hello():\n    print('hi')\n",
  "language": "Python",
  "commentsRemoved": 1,
  "linesRemoved": 1
}

POST/api/v1/detect

Detect the programming language of source code using extension, shebang, and content analysis.

Parameters

Name	Type	Required	Default	Description
code	string	Yes	—	Source code to analyze
filename	string	No	—	Filename for extension-based detection

Request

{
  "code": "def hello():\n    print('hi')",
  "filename": "app.py"
}

Response

{
  "language": "python",
  "name": "Python",
  "confidence": "high",
  "extensions": [".py", ".pyw", ".pyi"]
}

GET/api/v1/languages

List all 55 supported languages with their comment syntax and features. Cached for 24 hours.

Response

{
  "count": 55,
  "languages": [
    {
      "id": "javascript",
      "name": "JavaScript",
      "extensions": [".js", ".jsx", ".mjs", ".cjs"],
      "lineComment": ["//"],
      "blockComment": [{ "start": "/*", "end": "*/" }],
      "features": {
        "hasRegexLiterals": true,
        "shebangs": false,
        "docstrings": false,
        "nestedBlockComments": false,
        "rawStrings": false
      }
    }
  ]
}

Try It

Test the API right here. Paste code, pick a language, hit Run.

Try it live

Code Examples

Call the API from any language.

curl -X POST https://uncommenter.com/api/v1/uncomment \
  -H "Content-Type: application/json" \
  -d '{
    "code": "const x = 1; // comment\nlet y = 2; /* block */",
    "language": "javascript"
  }'

npm Package

Import the engine directly. Zero runtime dependencies. CJS + ESM + full TypeScript definitions.

$ npm install uncommenter

Quick Start

import { uncomment } from "uncommenter";

const result = uncomment(
  'const x = 1; // this is a comment',
  'javascript'
);

console.log(result.processed);       // "const x = 1;\n"
console.log(result.commentsRemoved); // 1
console.log(result.language);        // "JavaScript"

Auto-Detection

import { uncomment, detectLanguage } from "uncommenter";

// Detect by filename extension
const result = uncomment(code, undefined, "app.py");

// Detect by content analysis
const lang = detectLanguage(code);
console.log(lang.name); // "Python"

Low-Level Parser

import { removeComments, languageMap, DEFAULT_OPTIONS } from "uncommenter";

const config = languageMap.get("python")!;
const { result, commentsRemoved } = removeComments(
  source,
  config,
  { ...DEFAULT_OPTIONS, preserveTodos: true }
);

Exports

// Functions
export { uncomment } from "uncommenter";
export { removeComments } from "uncommenter";
export { detectLanguage, detectByExtension, detectByShebang, detectByContent } from "uncommenter";

// Data
export { languages, languageMap, extensionMap } from "uncommenter";

// Types
export type { LanguageConfig, UncommentOptions, UncommentResult } from "uncommenter";
export { ParserState, DEFAULT_OPTIONS } from "uncommenter";

CLI

Strip comments from files and directories right from your terminal.

$ npm install -g uncommenter

Commands

# Process a single file in-place
uncommenter src/app.ts

# Write to output file
uncommenter src/app.ts -o clean/app.ts

# Recursive directory processing
uncommenter src/ -r

# Pipe mode (stdin to stdout)
cat main.py | uncommenter --stdin -l python

# Show colored diff (no changes written)
uncommenter src/app.ts --diff

# Preview what would change
uncommenter src/ -r --dry-run

# List all 55 supported languages
uncommenter languages

Flags

Flag	Description
-r, --recursive	Process directories recursively
-l, --language <lang>	Force language (skip auto-detection)
-o, --output <path>	Write output to file
-d, --diff	Show colored diff
--dry-run	Preview changes without writing
--stdin	Read from stdin, write to stdout
-g, --glob <pattern>	Filter files by extension
--exclude <dirs>	Comma-separated dirs to exclude
--preserve-docstrings	Keep docstrings (default: true)
--no-preserve-docstrings	Remove docstrings
--preserve-todos	Keep TODO/FIXME comments
--preserve-shebangs	Keep shebangs (default: true)
--no-preserve-shebangs	Remove shebangs

Config File

Create a .uncommenterrc file in your project root:

.uncommenterrc

{
  "preserveDocstrings": true,
  "preserveShebangs": true,
  "preserveTodos": false,
  "exclude": ["node_modules", "dist", ".git", "vendor"]
}

Real-World Examples

# Clean up a TypeScript project before shipping
uncommenter src/ -r -g "*.ts" --no-preserve-docstrings

# Preview changes to Python files, keeping TODOs
uncommenter lib/ -r -g "*.py" --preserve-todos --diff

# Process a single file, output to new location
uncommenter legacy/app.js -o clean/app.js

# Pipe through in a shell script
cat input.sql | uncommenter --stdin -l sql > clean.sql

# Clean everything except tests
uncommenter src/ -r --exclude "tests,__mocks__"

Errors & Limits

Error Responses

Code	Error	Description
400	Bad request	Missing or invalid "code" field, or unknown language
413	Payload too large	Code exceeds 1MB limit
429	Too many requests	Rate limit exceeded (100 req/min)
500	Internal server error	Processing failed unexpectedly

Rate Limiting

The API is rate-limited to 100 requests per minute per IP. Rate limit headers are included in every response:

X-RateLimit-Limit: 100
X-RateLimit-Remaining: 97
X-RateLimit-Reset: 1706745600

When the limit is exceeded, you'll receive a 429 response with a Retry-After header indicating when you can retry.

Limits

Limit	Value
Max request body	1 MB
Rate limit	100 requests / minute
Languages supported	55
API key required	No
CORS	All origins allowed

API & DeveloperTools

REST API

npm Package

CLI

REST API

Parameters

Request

Response

Parameters

Request

Response

Response

Try It

Try it live

Code Examples

npm Package

Quick Start

Auto-Detection

Low-Level Parser

Exports

CLI

Commands

Flags

Config File

Real-World Examples

Errors & Limits

Error Responses

Rate Limiting

Limits

API & Developer
Tools