Base64 Decode Online
Decode Base64 and Base64URL strings into readable text, formatted JSON, or hex dumps with automatic JWT detection.
Base64 Input
Decoded Output
How to Use
- Paste a Base64 string, JWT token, or data URI in the input panel.
- The tool auto-detects the input format and shows a badge (Standard, URL-safe, JWT, Data URI).
- Switch between Text, JSON, Hex, or JWT output tabs to view the decoded data.
- Copy the output or download it as a file.
Common Use Cases
Debugging API tokens: Paste a JWT or OAuth token to inspect its header and payload claims (algorithm, expiration, roles, etc.).
Inspecting encoded payloads: Many APIs return Base64-encoded data in webhooks, event payloads, and message queues. Decode them to understand the content.
Data URI analysis: Extract and inspect the content of Base64 data URIs used in HTML images, CSS backgrounds, and font embedding.
Binary file inspection: Decode Base64 representations of small binary files and view a hex dump to analyze byte-level structure.
Related Tools
- Base64 to JSON Converter — specialized for JSON output with audit trail and encoding detection
- JSON to Base64 Converter — encode JSON into Base64 or Base64URL format
Frequently Asked Questions
What is Base64 encoding?
Base64 is a binary-to-text encoding scheme that represents binary data using 64 ASCII characters (A-Z, a-z, 0-9, +, /). It is widely used to encode data in URLs, email attachments, API tokens, and embedded images.
What is the difference between Base64 and Base64URL?
Base64URL replaces "+" with "-" and "/" with "_" to make the encoded string safe for use in URLs and filenames. It also typically omits padding "=" characters. This tool auto-detects both formats.
Can this tool decode JWT tokens?
Yes. When you paste a JWT (three dot-separated Base64URL segments), the tool detects it automatically and shows the decoded header and payload as formatted JSON, plus the raw signature.
What if the decoded output is binary?
The tool auto-detects binary content and shows a hex dump view with offset, hex bytes, and ASCII representation. You can also switch to hex view manually for any input.
Does this tool handle missing padding?
Yes. When auto-padding is enabled (the default), the tool automatically adds missing "=" characters before decoding. This fixes common issues with Base64URL strings.
Is my data uploaded to a server?
No. All decoding happens entirely in your browser. Your data never leaves your machine.
How is this different from the Base64 to JSON tool?
The Base64 to JSON tool is specialized for decoding Base64 that contains JSON and provides JSON-specific features. This tool is a general-purpose decoder that handles text, JSON, binary, JWTs, and data URIs with format auto-detection.