Encode a file. Inspect a token. Get back to work.
Base64 Converter Pro is a browser toolkit for developers and administrators who need to move between files, encoded text and readable data. Conversions run on your device. There's no account to create and no upload service.
Open the app · Download for offline use · User guide
| You have | Open | What you get |
|---|---|---|
| Files or a folder | File Encode | Encoded output, a batch ZIP, optional hashes and code snippets |
| Text to convert | Text | Live Base64, Base64URL, Hex, URL, UTF-7 or IMAP UTF-7 conversion |
| A Base64 string or data URI | Decode | A file download, media preview, hex dump or padding repair |
| A JSON Web Token | JWT | Readable claims and optional HMAC signature verification |
File encoding also supports Base32, Bitcoin Base58, Base62 and ASCII85. Those four formats are encode-only and belong in the File Encode tab. The Decode tab reads Base64 and Base64URL, not every format in the selector.
Text conversion keeps the input beside the output. Per-line mode handles a list without merging it into one value.
Inspect JWT claims without sending a token to a token-decoding service. A decoded token isn't automatically trustworthy: a signature check and your application's authorization rules still matter.
Other tools include image resizing, QR export and PEM wrapping. The guide explains their limits, including browser-dependent image formats and certificate parsing.
Use the hosted app. In a browser that supports installation, use Install as app or the browser's install control. Installation availability depends on the browser and platform.
For a disconnected machine, download the offline ZIP from Releases, extract it and open index.html. Keep the vendor folder beside it. The required libraries are included, so first use doesn't need a CDN connection.
Service-worker caching and installation need HTTPS or a localhost server. For local serving with Node.js 22 or newer:
git clone https://github.com/SysAdminDoc/Base64Converter.git
cd Base64Converter
node tools/serve.cjsOpen http://127.0.0.1:8080. No package installation is needed to run this server or use the app. Clear the app's site data if an older cached version persists, but export anything you want to keep first.
- File and text conversions run in the browser. The app has no conversion backend or analytics code. Opening the hosted app still makes ordinary page requests to GitHub Pages.
- Save to history is on by default for file conversions. It keeps up to 50 entries in browser storage, with an 8,000-character preview per result and a total size limit. Turn it off before handling sensitive files. History → Clear removes stored entries; Clear All only clears the current file list.
- Fetch contacts the URL you enter. Share sends output to the destination you choose. A shareable link includes the data in its URL, which can appear in history and server logs. Don't use links for secrets.
- Encoding isn't encryption. Use sample tokens and test keys when possible. This tool doesn't validate certificate chains, revoke tokens or make authorization decisions.
The application is static HTML, CSS and JavaScript. A worker handles file encoding. Two pinned libraries are bundled locally with their licenses in vendor.
npm ci
npx playwright install chromium
npm test
npm run test:browser
npm run buildAfter editing the inline application script, run npm run sync:security to update its Content Security Policy hash. The build checks that hash and packages the app locally. No hosted build service is used.
See the release notes, verification notes and preserved concepts. Screenshots use harmless sample data. No mockup is presented as a working product screen.
MIT. Bundled libraries retain their own MIT notices.