Free · no sign-up · nothing uploaded
Base64 Decoder Online Free
Paste Base64 — standard or URL-safe, with or without a data: prefix — and read the decoded UTF-8 text instantly. Built for debugging JWTs, API responses and config values without installing anything.
Decode Base64
Live decoding · 100% in your browser · no network round trip
Whitespace, line breaks and URL-safe -_ characters are handled automatically.
How it works
Three steps, no account, no upload — the whole pipeline runs on your device.
Drop a Base64 blob into the box, or load a .txt/.b64 file up to 2 MB. A data:…;base64, prefix is stripped for you.
Line breaks, spaces, URL-safe -_ characters and missing padding are fixed automatically, and the hint line tells you what was changed.
Valid UTF-8 appears as text; binary payloads switch to a hex dump. Copy it or download it as a .txt file.
Why this decoder
Decoding happens as you type — no request, no queue. A 500 KB blob resolves well under 100 ms and works with the tab offline.
Wrapped lines, copied whitespace, base64url variants and missing = padding still decode. Unrecoverable input gets a plain-English message, never a crash.
Bytes that are not valid UTF-8 (PNG, GZIP, protobuf) automatically fall back to an offset/hex/ASCII dump instead of showing mojibake.
UTF-8, Latin-1 and UTF-16LE are one click apart, so legacy config values and Windows exports decode correctly too.
Your Base64 never leaves the browser — there is no server endpoint for it and no analytics on the content.
Free and unlimited for the everyday debugging loop: tokens, API payloads, email attachments, config values.
FAQ
Is my Base64 uploaded anywhere?
No. The page has no server endpoint for decoding — atob and TextDecoder run in your browser, so tokens and payloads stay on your machine.
Why does my decoded text show squares or a hex dump?
The bytes are not valid UTF-8 — common for images, archives and encrypted data. The decoder switches to a hex dump automatically instead of showing replacement characters. Pick another charset, or switch to Hex / bytes yourself.
Does it handle URL-safe Base64 and JWT segments?
Yes. - and _ are translated to + and /, missing = padding is added, and a data: prefix is removed. Paste a JWT payload segment directly.
What are the size limits?
Files up to 2 MB load automatically. Larger pastes are allowed but pause behind a Decode anyway button, and long previews are truncated — the Copy and Download buttons always give you the full output.