Decode Base64 strings and pretty-print JSON data — paste encoded text to see the decoded result instantly. Inspect API payloads and tokens readably — free, local, no signup.
Content reviewed October 2026 · About Toolzum
Decode and inspect JWT tokens — view header, payload, expiration, issuer, subject, and other standard claims. Paste an HMAC secret to genuinely verify HS256/384/512 signatures — local inspection, free, no signup.
Generate random tokens in hex, base64, or alphanumeric formats for secrets and sessions. Hex and base64 draw from Web Crypto (alphanumeric uses Math.random — see format notes). The API-key preset mints 64-char secrets in one click — local generation, free, no signup.
Decode JWT headers and payloads instantly — inspect claims, expiry, and algorithm before trusting a token. Debug auth failures in seconds — local processing, free, no signup.
Encode images to Base64 data URIs for CSS embedding and API payloads. Inline a logo without extra requests — local encoding, free, no signup.
Decode binary strings back to readable Unicode text with strict validation. Recover messages from bit dumps — local decoding, free, no signup.
Decodes the Base64 string to its original text, then attempts to parse it as JSON. If successful, the JSON is pretty-printed with syntax highlighting.
Yes. Paste any Base64 string and the tool attempts to decode it. If the result is valid JSON, it's automatically pretty-printed.
Yes. You can paste either Base64-encoded JSON or raw JSON. Raw JSON is directly pretty-printed without Base64 decoding.
Yes. Deeply nested JSON objects and arrays are formatted with proper indentation (2 spaces) and syntax highlighting for easy reading.
No. All decoding and formatting happens locally in your browser. No data is transmitted to any server.
Image to Base64
Encode images to Base64 data URIs for CSS embedding and API payloads. Inline a logo without extra requests — local encoding, free, no signup.
JSON Formatter
Pretty-prints raw JSON with configurable indent width, key sorting, and bracket collapsing options while flagging syntax errors with exact.