Base64 Encode & Decode Online
Convert plain text to Base64 or decode Base64 back to readable text. Useful for API payloads, Basic Auth headers, JWT segments, and debugging data transfers. Base64 is encoding, not encryption—it is reversible by anyone.
What is Base64 encoding?
Base64 is a way to represent binary data using only ASCII letters, digits, and a few symbols (+, /, with = padding). It is commonly used in HTTP Basic Authentication headers, JSON Web Tokens (JWT), email (MIME), and API payloads that must travel through text-only channels. CompareStack’s Base64 tool encodes plain text to Base64 or decodes Base64 back to readable output.
Important: Base64 is not encryption. Anyone can decode it. Do not treat Base64-encoded passwords or secrets as secure.
How to use Base64 encode and decode
- Paste your text or Base64 string into the input field.
- Click Encode to Base64 to convert plain text into a Base64 string.
- Click Decode from Base64 to reverse a Base64 string back to text (or hex for binary data).
- Copy the result for your API client, script, or documentation.
Common use cases
- Inspect the payload segment of a JWT (after decoding header and signature separately in your security workflow)
- Build or verify HTTP Basic Auth credentials (
base64(username:password)) - Decode API responses that return Base64-encoded files or snippets
- Prepare small text blobs for inclusion in JSON or XML where binary is not allowed
Decode tips and errors
Valid Base64 uses characters A–Z, a–z, 0–9, +, and /, with = padding at the end when needed. Whitespace in pasted strings is ignored. If decoding fails, check for truncated copy-paste, URL-safe variants (use - and _ instead of + and / in some systems), or corrupted data.
When decoded bytes are not valid UTF-8 text, CompareStack shows a hexadecimal view so you can still inspect binary content safely.
Related tools
- URL Encode / Decode — percent-encoding for query strings
- JSON Formatter — validate API payloads
- Text Compare — diff encoded or decoded versions
Base64 in APIs and auth
Use encode for quick inspection of what goes into a Basic Auth header or binary-safe JSON field—then decode on the receiving side in your app.
JWT middle segments are Base64URL, which may differ slightly from standard Base64; translate - and _ if decode fails.
Never store passwords using only Base64; pair proper secret management with transport encryption (HTTPS).
Tool FAQ
Is Base64 the same as encryption?
No. Base64 is encoding—anyone can decode it. Do not use it alone to protect passwords or secrets.
What can I encode?
You can encode any text you paste into the tool. Very large inputs may take longer within the size limit on the page.
Why does decode fail?
Invalid characters, wrong padding, or truncated strings cause decode errors. Remove stray spaces and verify the full Base64 string was copied.
What is URL-safe Base64?
Some systems use - and _ instead of + and /. This tool uses standard Base64; translate characters if your API expects URL-safe variant.