B64
No signupBase64 Encoder
Encode text to Base64, with correct Unicode handling.
Open toolB64
Base64 Decoder
Decode Base64 back to readable text, with correct Unicode handling.
base64.tool
0 chars
Result will appear hereNothing you paste here is ever sent to a server - conversion happens locally in your browser.
What is a base64 decoder?
This tool decodes Base64-encoded text back into its original, readable form. Base64 shows up constantly in API responses, JWTs, Basic Auth headers, and data URIs - this tool turns that block of letters and symbols back into something you can actually read, with correct Unicode handling.
How to use this tool
- 1Paste the Base64 string you want to decode (or upload a .txt file containing it).
- 2The decoded text appears instantly on the right.
- 3Use Swap to flip to encode mode using the current output as the new input.
- 4Copy the result or download it as a file.
Common use cases
Decoding the header or payload segment of a JWT by hand
Reading the contents of a Basic Auth Authorization header
Inspecting a Base64 blob found in an API response or log file
Checking what a data URI actually contains
Good to know
Frequently asked questions
Why did I get an error decoding my string?
The input isn't valid Base64 - usually because of missing padding characters, stray whitespace, or characters outside the Base64 alphabet (A–Z, a–z, 0–9, +, /). Double-check you copied the full string.
Does this handle Base64URL (the variant used in JWTs)?
This decoder expects standard Base64. JWTs use Base64URL, which swaps + and / for - and _ and omits padding - for decoding JWT segments specifically, use the dedicated JWT Decoder tool, which handles that variant automatically.
Can decoded output contain non-printable characters?
If the original data wasn't UTF-8 text (for example, actual binary data), decoding may show unexpected characters - this tool is built for decoding Base64 that represents text.
Is my data uploaded anywhere?
No - decoding happens entirely in your browser.
quick_facts.json
{
"runs_in_browser": true,
"data_sent_to_server": false,
"signup_required": false,
"price": "free",
"category": "Encoding"
}