About

DevLab is a developer support site for web developers, QA engineers, and infrastructure engineers.

We provide one-stop access to URL-based website diagnostics (security, SEO, LLMO, structured data), browser-only data conversion and generation tools, dummy files for testing (images, PDF, CSV, ZIP, etc.), and format reference cheatsheets.

All services are free to use, with no signup required.

Every conversion and generation tool runs entirely inside your browser. The text you type and the images or PDFs you open are never sent to our servers and leave no record on our side. That these tools keep working offline is itself the proof of that property.

The exceptions are the few things that cannot work any other way. The diagnostic tools fetch the URL you give them from our server. OCR and the high-accuracy furigana mode process the uploaded file with Tesseract or MeCab on the server and discard the input once the response has been returned. Neither writes the request body to a log.

The site is funded by advertising. Using it never requires an account, a payment or an email address. We use Google Analytics for traffic measurement; the details are in the privacy policy.

Articles and reference pages are written against the published specifications and implementations, and updated when those change. If you spot an error, or want a tool we do not have yet, tell us through the contact form. What has changed and when is published on the changelog page.