Base64 Encode/Decode
Encode and decode Base64 strings in the browser
Input
Output
Encode and decode Base64 without trusting an online server
Base64 shows up everywhere — JWT payloads, image data URIs, email attachments, API request bodies. Encoding and decoding it in your browser keeps the data on your machine, which matters when the value is a token, a secret, or anything else you'd rather not paste into a remote service.
Use the tool when you need to
Decode a Base64-encoded value from a header
Inspect Authorization headers, encoded query parameters, or other Base64 strings safely in the browser.
Encode binary data for an API
Convert a small image or file into a Base64 string for inclusion in a JSON request body.
Flip between Base64 and Base64URL
Switch encoding variants when working with JWTs and URL-safe payloads.
How to encode or decode Base64 quickly
- 1
Paste the input into the text area.
- 2
Click Encode or Decode based on the direction you need.
- 3
Copy the result, or download it as a file when working with binary data.
Keep going
Encode URL components
Use percent-encoding when the destination is a URL rather than binary safety.
Decode JWTs
Use the focused decoder when the Base64 value is part of a token.
Format decoded JSON
Beautify the output if the decoded value turns out to be JSON.
Validate decoded JSON
Confirm the decoded JSON parses cleanly before passing it forward.
Common Base64 workflows
Decode a Basic auth header to see the raw username and password format being sent.
Encode a tiny image as a data URI and embed it directly in an API request body.
Decode a JWT segment, edit it, and re-encode it for testing — without server-side help.
Related Tools
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JWT Decoder
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JSON Validator
Validate API and AI-generated JSON with detailed error messages and line numbers
Frequently Asked Questions
Base64 encodes binary data into ASCII text using 64 printable characters (A-Z, a-z, 0-9, +, /). It's used to embed binary data in text-based formats like JSON, XML, HTML, and email. The encoded output is roughly 33% larger than the input.
Paste your text in the input field and click Encode. The tool converts each character to its UTF-8 bytes and then to Base64 representation. Click Copy to grab the result.
Common uses include: embedding small images in CSS/HTML (data URIs), sending binary data in JSON APIs, encoding file contents for upload, email attachments (MIME), and storing binary data in text-only databases.
Standard Base64 uses + and / characters, which need escaping in URLs. Base64URL replaces these with - and _ and removes padding (=). JWTs use Base64URL encoding because tokens are often passed in URLs.