Base64 encode / decode (standard & URL-safe)
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About Base64 encode / decode (standard & URL-safe)
This tool runs entirely in your browser. Use it to encode or decode Base64 for UTF-8 strings, or to convert small binary files to Base64 (encode path). Standard encoding uses + and / with padding. URL-safe replaces those characters and is common in JWT and query parameters. It is a developer convenience — not a replacement for proper secrets management or transport security.
Key Features
- UTF-8 text encoding and decoding (not raw Latin-1 only)
- Standard vs URL-safe alphabet toggle
- Small file drop for raw-byte encode (e.g. images, keys) with a 256KB limit
- Copy result without an account or server round-trip
Use Cases
- Quickly check what a data: URL or blob of Base64 represents
- Prepare URL-safe token segments for webhooks and APIs in docs
- Decode a Base64 string from a log line locally
Pro Tips
- URL-safe mode strips padding; some systems still expect = padding when decoding
- For secrets, prefer env vars and key vaults over pasting in any online form
- Very large files should use CLI tools — this cap keeps the tab responsive
Frequently Asked Questions
Is my data sent to AllOneTools?
No. The conversion uses your browser (FileReader, btoa/atob, TextEncoder).
Why does my decode fail?
Invalid characters, wrong padding, or non-Base64 data will throw. For URL-safe input, select URL-safe before decoding.
Is this the same as Node Buffer?
Conceptually similar for UTF-8 text. For binary file encode we use raw bytes from an ArrayBuffer.