Decode Base64, Base64URL (RFC 7515), JWT payloads, and JSON data URIs into readable JSON. Features automatic content detection, live JSON syntax validation with line/col error markers, interactive tree viewer, 6-bit step-by-step visualizer, batch ZIP export, and 100% browser privacy.
Base64 encoding translates binary data or UTF-8 text into a 64-character printable ASCII string (RFC 4648). In modern web applications, microservices, and mobile APIs, JSON payloads are frequently encoded into Base64 to safely pass structured data inside HTTP headers, query parameters, database text fields, or JSON Web Tokens (JWTs).
Standard Base64 contains + and / characters which conflict with URL syntax. Base64URL replaces + with - and / with _, stripping trailing = padding. This format is the standard encoding used in OAuth 2.0, OpenID Connect, and JWT token headers and payloads.
All decoding, JSON parsing, syntax validation, tree construction, and cryptographic SHA-256 hashing execute 100% locally in your web browser using HTML5 Web APIs and Web Workers. Zero bytes are uploaded to remote servers.
Base64 to JSON conversion decodes a Base64-encoded string (or URL-safe Base64URL string) back into raw text, automatically parses it as JSON, formats it with pretty print, and structures it into an interactive JSON tree for easy inspection.
Standard Base64 uses the characters + and / with = padding. Base64URL replaces + with - and / with _, and omits trailing = padding, making the encoded JSON string safe for HTTP headers, URL query parameters, and JWT tokens.
Once decoded, our engine inspects the text structure to determine whether it is a JSON Object, JSON Array, JWT Token, XML, YAML, HTML, CSV, or plain text. If it is valid JSON, it instantly parses and builds an interactive tree.
If the decoded text is not valid JSON, the validator highlights the exact line number, column number, and error explanation (e.g. missing quotes, trailing commas) and suggests quick automated fixes.
Yes! When a full JWT token (header.payload.signature) is detected, the tool decodes both the Header and Payload segments into pretty-printed JSON and displays the raw Signature separately. Note: JWT decoding does not verify signature authenticity.
A Data URI allows complete files to be embedded inline using the syntax "data:[mime];base64,[payload]". Our tool automatically extracts the Base64 payload from data URIs and decodes the embedded JSON.
Base64 encoding translates every 3 binary bytes into 4 ASCII characters, resulting in an exact 33.33% size expansion. Decoding Base64 back to JSON shrinks the input string size back to its original raw byte count.
The visualizer breaks down the Base64 string into individual 6-bit index offsets, maps them into 24-bit binary groups, reconstructs the original 8-bit bytes, and converts them back into UTF-8 characters and JSON text.
Absolute NO. All decoding, JSON parsing, validation, tree generation, and Web Crypto hashing run 100% client-side inside your browser. Zero data is transmitted to external servers.
Yes! Switch to ⚡ Batch Mode to upload multiple Base64 or text files simultaneously. The tool decodes and validates each file in parallel and allows you to export all decoded JSON files inside a single ZIP archive.
The tool automatically computes SHA-256 and SHA-1 cryptographic hashes of the decoded buffer using the native Web Crypto API (crypto.subtle.digest) to verify payload integrity.
Yes! Built-in controls allow you to Pretty Print (2 or 4 spaces), Minify, Sort Object Keys alphabetically, or remove null properties with a single click.
Clicking any node in the Interactive JSON Tree displays a "Copy JSON Path" button, allowing you to quickly extract nested paths like `user.addresses[0].city` for your code.
All modern browsers including Google Chrome, Mozilla Firefox, Apple Safari, Microsoft Edge, and mobile browsers on iOS and Android fully support browser-local Base64 to JSON conversion.
Encode valid JSON into Base64 or Base64URL with UTF-8-safe processing, serialization controls, and a compact size audit.
Decode Base64 and Base64URL strings into text, JSON, or hex with JWT detection and format auto-detection.
Encode text and files into standard Base64 or Base64URL with line wrapping, data URI generation, and large file support.