Decode Base64
Paste Base64 and get back what it was — text, an image, a PDF, anything. Broken padding, line wrapping and URL-safe variants are all repaired automatically. Nothing is uploaded.
- Processed on your device
- No upload, no waiting
- No signup, no watermark
Paste Base64 and whatever it decodes to appears here.
How it works
Paste the Base64
Wrapped, unpadded, URL-safe or inside a PEM block — all are accepted and each repair is reported.
See what it was
Text is shown as text. Binary is identified by its own bytes — PNG, PDF, ZIP — and offered as a download with the right extension.
Copy or save
Copy the text, or download the recovered file.
Frequently asked questions
Is my Base64 uploaded?
No. Nothing is uploaded, nothing is logged, and no request leaves your device — the work happens inside this page, in JavaScript, and it keeps working with the network disconnected. For these tools in particular that is not a nicety. What people paste into online encoders and decoders is routinely live: session tokens, API keys, Authorization headers, customer records. Pasting one of those into a page that sends it somewhere is a disclosure, whatever the site promises about deletion.
It says invalid Base64, but I copied it correctly
Four things commonly break a copied string, and all four are repaired here automatically rather than refused. Line breaks from email headers, PEM blocks or MIME wrapping are removed. Missing = padding is added. The URL-safe alphabet (- and _ instead of + and /) is detected and translated. And spaces are tried BOTH ways — as incidental whitespace, and as + characters that a URL turned into spaces, which is what happens whenever Base64 travels through a query string. Each repair is named in the result, so you can see what your string actually was. If it still fails, a character was genuinely lost in copying, and the page says which.
Can it decode a JWT?
It will decode each part, but the JWT Decoder is the better page for that — it splits the three sections, formats the JSON, turns the timestamps into real dates and tells you whether the token has expired. Do not paste a live session token into a general decoder anywhere; on this site it stays on your device either way, but that is not true of most.
What happens with an image or a PDF?
It is recognised and offered as a download. The file type is identified from the decoded bytes themselves rather than from anything you tell us — a PNG signature, a PDF header, a ZIP marker — so the download gets the right extension even when the original name is long gone. Images are previewed in the page.
What does "read as Base64URL" mean in the result?
That your string used the URL-safe alphabet, where - and _ stand in for + and /. It is the variant used by JWTs, OAuth and anything carried in a URL. The two alphabets decode to different bytes, so getting this wrong produces silent corruption rather than an error — it is detected and reported rather than assumed.
Can I decode something someone sent me safely?
Decoding itself is safe — nothing is executed, and it happens on your own device. But be careful with what comes out. Base64 is a common way to hide a malicious script or executable from a mail filter, so treat a decoded file from an unexpected source exactly as you would treat an unexpected attachment.
Is there a size limit?
Your device's memory rather than an upload cap. Large strings decode fine.