Base64 Decoder
Paste your Base64. Read it instantly.
Free Tool — No Login RequiredBase64 Encoding
Need to encode text or a file to Base64?
Use our Base64 Encoder for text, URLs, files, and images.
What is Base64 Decoding?
Base64 decoding is the process of converting a Base64-encoded string back into its original readable form — plain text, JSON, URLs, or binary content. Base64 is widely used in REST APIs, JWT tokens, email MIME encoding, and data storage. When you receive a Base64 string and need to read its original content, a Base64 decoder instantly reverses the encoding back to human-readable text entirely inside your browser.
Why Use CodeZiper's Base64 Decoder?
- Instantly decode any Base64 string to plain text
- Supports standard Base64 and URL-safe Base64URL (RFC 4648)
- Auto-detect URL-safe format — no manual toggle needed
- Auto-fix missing = padding characters automatically
- Smart JSON detection — links to JSON Formatter when output is JSON
- Upload .txt or .b64 files directly for offline string decoding
- Download decoded output as .txt or .json file
- Full Unicode support — handles all languages and special characters
- 100% browser-based — your data never leaves your device
- No signup, no login, completely free
Common Use Cases
JWT Token Inspection
Decode the payload section of JWT tokens to inspect user claims, roles, expiry timestamps, and permissions during API development and debugging.
API Response Debugging
Decode Base64-encoded fields in REST API responses, webhook payloads, and HTTP Basic Auth headers to read the raw transmitted data instantly.
Email & MIME Decoding
Decode Base64-encoded email body content and MIME attachments received from mail servers, email APIs, or SMTP logs.
Decoder FAQ
Common questions about this tool.
Base64 decoding converts a Base64-encoded string back into its original plain text or binary data. It is the exact reverse of Base64 encoding.
Standard Base64 uses + and / characters. URL-safe Base64 (Base64URL) replaces + with - and / with _ so the string is safe to use in URLs and filenames. Enable URL-Safe Mode or Auto-Detect if your string contains - or _ characters instead of + and /.
Common causes are missing = padding characters, illegal characters in the string, or whitespace. Enable Auto-Fix Padding to handle missing padding automatically. The tool also strips whitespace before decoding.
No. All decoding runs entirely in your browser using JavaScript's built-in atob() function. Nothing is sent to any server.
Yes. Copy the middle part (payload) of your JWT — the section between the two dots — paste it here, enable URL-Safe Mode (JWTs use Base64URL), and decode it to read the claims.
The tool automatically detects valid JSON in the decoded output and shows a tip linking to the JSON Formatter so you can view the data in a clean, structured tree format.
Yes. Use the upload button in the input panel to load a .txt or .b64 file. The file content will be loaded into the input and decoded automatically.