4coders
your input never leaves this tab

4coders — tiny tools, big grin

Client-side Base64, JWT, JSON, hashes, QR codes & more. Everything runs in your browser — your input is never uploaded.

Press Ctrl K to jump anywhere — or pick a tool below.

Free client-side developer tools — your input never leaves your browser

Encode / Decode

Base64Encode & decode Base64 — URL-safe, UTF-8 aware.URL / PercentPercent-encode & decode URLs and query strings.HTML EntitiesEscape & unescape HTML entities — no innerHTML.HexText to UTF-8 hex bytes and back.BinaryText to 8-bit binary and back.Unicode Escapes\uXXXX escapes — surrogate-safe.Base32RFC 4648 Base32 encode & decode.ROT13 / CaesarRotate letters by any shift (13 = ROT13).MorseText to Morse code and back.

Inspectors

JSONFormat, minify & validate JSON — errors inline.JWTDecode a JWT — header, payload, claim times. Never sent.TimestampUnix epoch to date and back — local, UTC, ISO.Diff & RevealDiff two blobs; reveal hidden characters.

Hashing

HashMD5, SHA-1/256/384/512, CRC32 at once — plus compare.

Generators

UUIDGenerate random UUID v4s — copy on click.PasswordStrong secrets with live entropy — CSPRNG.

Barcodes & QR

QR CodeText, URL, Wi-Fi, vCard → QR. Download SVG/PNG.BarcodeCode128, EAN-13, UPC-A, Code39, ITF. SVG/PNG.

Why client-side tools?

  • • Your input never leaves your machine. Paste tokens, secrets or private data with confidence.
  • • No server round-trips: the work happens in your browser, so a tool you are already using keeps working even if your connection drops.
  • • Fast, keyboard-first experience with ⌘K / Ctrl K palette, live updates and one-click copy chains.
  • • No accounts, no tracking pixels on your inputs, no ads. Just the utilities you need.

Common questions

Do you upload or store anything I paste?

No. Every single conversion, hash, decode and generation runs locally in your browser using Web APIs and small pure-JS libraries.

Can I use 4coders without internet?

Partly. 4coders has to load from the internet and does not install an offline copy. A tool you are already using keeps working if your connection drops, because the work happens in your browser (QR and barcode fetch their renderer on first use); reloading or opening another tool needs the connection again.

Is this a replacement for CyberChef or jwt.io?

It's a focused, fast, privacy-first subset. If you love small dedicated tools that respect your data, you'll feel at home here.