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Developer tools

4 free developer tools — no signup, instant results.

Inspect API responses, compare data changes and decode encoded content locally. Choose a tool by the question you need to answer: readable structure, changed values, token contents or transport encoding.

All developer tools

Base64 Encoder/DecoderDeveloper

Convert text or local files using standard or URL-safe Base64 — free, instant, and private.

JSON Diff CheckerDeveloper

Compare two JSON documents and see exactly which keys were added, removed, or changed, with the full path to each — free and instant.

JSON FormatterDeveloper

Format, validate, and minify JSON instantly — free, private, and works entirely in your browser.

JWT DecoderDeveloper

Decode and inspect a JSON Web Token (JWT) — see its header and payload instantly, entirely in your browser.

Choose a tool for your task

JSON Formatter
Use this when a response is hard to read or a configuration file has a syntax error. Import a local file, inspect the tree and export formatted JSON.
JSON Diff Checker
Use this when two responses are both valid but behave differently. Compare their values and paths, with optional ignored fields and array ID matching.
JWT Decoder
Use this to inspect token claims. Decoding shows what a token contains; it does not establish that the issuer or signature is trustworthy.
Base64 Encoder/Decoder
Use this to encode text or a local file, or recover bytes from Base64. Base64 is an encoding, so it does not hide secrets from someone who can read the encoded value.

Investigate a changed API response

  1. Format each response and resolve syntax errors first. Keep the originals if exact number spelling or duplicate keys matter.
  2. Compare the two valid documents in JSON Diff Checker. Ignore a timestamp only after confirming it is irrelevant to the problem.
  3. For arrays of records, choose a stable ID field if order is incidental. Copy the changed paths into your bug report without including credentials or customer data.

What these tools can and cannot tell you

These tools inspect local data; they do not contact an API, validate a business schema or authenticate a user. JSON parsing uses JavaScript numbers, so large integers may lose precision and duplicate keys keep only the last value. Keep opaque identifiers as strings.

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