Free developer tools — Base64, JWT, sitemap & more
Every utility below is a dedicated URL you can bookmark: Base64 text encoding and decoding, image ↔ Base64 conversion, a JWT token inspector for header and payload, and an XML sitemap generator for sitemap.xml exports. We pair tools with the blog so you get both "how" and "when not to," not just a single textarea. No account, no install: open the page, paste input, and copy the result. The cards below list every public tool URL in one place for bookmarking and internal discovery.
Why use browser-based developer tools?
Privacy: Base64, JWT, and sitemap work runs locally in your tab whenever possible, so you are not batch-uploading files to a random server. Speed: no install, no version drift: the tool matches the page you have open. Shareability: send a colleague a URL that always opens the right workflow—encode, decode, image preview, or sitemap build—without bundling a desktop app. For teams, that cuts onboarding time: the JWT and Base64 tools explain limits (for example, JWT decode is not signature verification) right on the page.
How to choose the right encoding or SEO tool
| If you need… | Start here |
|---|---|
| Turn plain text into a Base64 string for JSON or config | Base64 encode |
| Read a Base64 string back to UTF-8 text | Base64 decode |
| Inline an icon or small asset (data URL / raw Base64) | Image to Base64 |
| Preview an image you only have as Base64 or a data: URL | Base64 to image |
| Read JWT header, payload, and exp/iat (debug, not auth) | JWT decoder |
| Hand off a sitemap.xml for Search Console or static hosting | XML sitemap generator |
| Try a regex against sample text with visible matches | Regex tester |
| Issue random v4 UUIDs for IDs and fixtures | UUID generator |
| Convert Unix time ↔ readable dates (local & UTC) | Timestamp converter |
All tool entry points
XML sitemap generator
Paste URLs, download sitemap.xml for SEO handoffs and static hosts.
JWT decoder
Inspect header, payload, and exp claim. Signature not verified in-browser.
Base64 encode
UTF-8 text to Base64 with autodetect, copy, and download.
Base64 decode
Base64 to readable text with common whitespace tolerance.
Image to Base64
Local file to data URL and raw Base64, no upload.
Base64 to image
Paste a payload, preview, and copy a normalized data URL.
Regex tester
Pattern, flags, live highlights — invalid regex surfaces as a clear error.
UUID generator
Cryptographically random v4 UUIDs — batch generate and copy locally.
Timestamp converter
Unix seconds or milliseconds ↔ calendar dates — local and UTC.