Six encoders/decoders in one page: Base64 (RFC 4648), URL encoding (RFC 3986), HTML entities, Unicode escape, JWT decode (claim reading, no signature verify), image to Data URI. Fully: input never leaves the browser, images never go up to a server.
Drop an image here or click to pick a file
Max 10 MB
Each tab is an independent function: Base64, URL, HTML entities, Unicode, JWT, Image to Data URI. Tab-specific options (URL-safe, named/numeric entities) appear inside the relevant tab.
For text tabs, paste into the input area. For image-to-data-uri, drop an image (PNG, JPEG, GIF, WebP, SVG) onto the dropzone or use the file picker.
The first five tabs work both ways. The image tab is one-way (binary file to text Data URI). To recover the file from a Data URI, just paste it in the browser address bar.
The Copy button pushes the result to your clipboard. The Swap I/O button moves the output back to the input area, useful for repeated encoding/decoding (e.g. Base64 of Base64, common in nested payloads).
Daily operations in one place. Base64 decode, URL encoding, HTML escape, JSON escape, UTF-8 conversion and Data URI inspection are operations every developer does multiple times a day. Having them all already loaded in the same tab eliminates the switch between tools and the first-load overhead of opening a different web page each time.
Image-to-Data-URI directly in the browser. Many similar web tools upload the file to a server, convert it there, return the Data URI: the sensitive image (product screenshot, unreleased logo, personal picture) transits through a third-party backend. Here the file is read via FileReader.readAsDataURL() directly in the browser, with no external transfer. The 10 MB limit prevents tab freezes on accidental drops of huge files; on modern machines you could technically push to 50-100 MB.
JWT decode in read mode. The tool decodes header and payload (Base64URL, JSON claims) but does not verify the signature: verification would require the backend's HMAC secret or RSA/ECDSA public key, which have no business transiting through a generic utility. For HS256 signature verification in WebCrypto and the dedicated claim explainer, see the JWT decoder; for the full security audit (alg=none, weak HS256, missing claims, oversized lifetime, kid injection) the dedicated tool is the JWT security audit.
Technical terms used on this page, briefly explained.
é) or numeric (é, é). HTML5 defines ~2200 named entities in the WHATWG spec. data:[mime];base64,[payload]. Replaces a separate fetch for the file, handy for small assets (icons, font subsets, badges). Practical limit: 32 KB on Internet Explorer, 256 KB on Chrome/Firefox. FileReader.readAsDataURL(), obtains the Data URI string in memory and renders it directly; no transfer to the server takes place during the operation.base64 -w 0 file.pdf on Linux/macOS, certutil -encode file.pdf out.txt on Windows.innerHTML on a node and read its textContent in DevTools.encodeURI preserves URL syntax characters (: / ? # & = +). Use it when you already have a formed URL and just need to make literal parameters safe. encodeURIComponent also encodes those characters. Use it for a single query string value (e.g. q=all&ok becomes q=all%26ok).Buffer.from(s, 'base64'), base64_encode()). It is three lines, no reason to wrap them in an HTTP API.Maurizio Fonte, senior IT consultant with 20+ years in PHP, Laravel, unmanaged Linux infrastructure, applied cybersecurity and AI/LLM integration. Production backends, legacy code modernization, security audits, custom AI agents and MCP servers: the work behind every tool published here.
About Maurizio Fonte