mdgate converters

SUB to Markdown in your browser.

Convert SUB files to GitHub-Flavored Markdown directly in your browser.

Your SUB stays on your device. No upload. No account.

Starting local converter

Use SUB to Markdown in your app

$ npm install @mdgate/subtitle 

import { toMarkdown } from '@mdgate/subtitle';

const markdown = await toMarkdown(bytes);

Pure TypeScript, Node.js, Cloudflare Workers, Edge, Browser, No Python, No native addons, No WASM, Zero third-party runtime dependencies

How SUB to Markdown works

  1. SUB
  2. cue parsing
  3. timing · text · emphasis
  4. GitHub-Flavored Markdown

Built for JavaScript runtimes

Node.js

Read local files, uploads, S3/R2 objects, and other byte sources.

Cloudflare Workers

Parse subtitle files directly inside Workers without a media player.

Browser

Convert SUB locally without uploading it to a server.

Edge

Run the same TypeScript converter in compatible Edge runtimes.

What @mdgate/subtitle extracts

  • SRT and WebVTT timing
  • ASS / SSA dialogue lines
  • LRC lyrics
  • MicroDVD .sub
  • YouTube .sbv
  • TTML
  • Jacosub .jss
  • Italic and other simple emphasis when the format carries it

Why @mdgate/subtitle

Runs where your JavaScript runs

No separate processing service. The converter is TypeScript you can call from Node.js, Cloudflare Workers, Edge runtimes, and browsers.

Local conversion

SUB files can stay inside your application or browser.

Content detection

Recognizes SUB files from their contents, not only the filename.

Deterministic parsing

The same SUB file produces repeatable Markdown without model inference.

Small runtime surface

No Python. No native addons. No WASM. No third-party runtime dependencies.

SUB for AI agents

Turn SUB files into content your agent can actually work with.

  1. SUB
  2. Markdown
    • grep
    • search
    • chunk
    • index
    • cache
    • cite
    • reason

Need more than SUB?

One format

@mdgate/subtitle

Your own set

@mdgate/core
+ @mdgate/subtitle
+ @mdgate/pdf
+ @mdgate/docx

Broad file support

@mdgate/converters

FAQ

Can I convert SUB to Markdown without uploading it?

Yes. SUB files can be converted locally in the browser.

Does SUB to Markdown work in Cloudflare Workers?

Yes. @mdgate/subtitle runs directly in Cloudflare Workers.

Does it require Python?

No.

Does it require native addons or WASM?

No.

What does it output?

GitHub-Flavored Markdown.

Can I install only the SUB converter?

Yes. Install @mdgate/subtitle instead of the complete converter set.