Find & Decode Base64
Paste text with embedded Base64 blobs (logs, JSON, headers, data URIs) and decode them all at once — text, or a file-type + hex preview for binaries. Runs in your browser; nothing is uploaded.
About this tool
Find & Decode Base64 scans a block of text, locates every embedded Base64 blob, and decodes it — so you don't have to copy each one into a decoder by hand.
For each blob it tells you:
- Decoded text — when the bytes are printable UTF-8.
- File type + hex preview — when the bytes are binary and match a known
format (e.g.
image/png,application/pdf), it shows the detected MIME type and the leading bytes in hex.
It understands both standard (+//) and URL-safe (-/_) Base64, with
or without padding. Random alphanumeric runs that decode to neither printable
text nor a recognized file type are ignored, to cut down on false positives.
Everything runs locally in your browser via WebAssembly — your text is never uploaded.
Handy for
- Inspecting JWTs, API tokens, and HTTP headers.
- Pulling readable content out of logs, JSON, or config dumps.
- Identifying what a
data:URI or embedded blob actually contains.
FAQ
Why wasn't my Base64 string detected?
Candidates must be at least 16 characters long (about 12 decoded bytes),
use one alphabet consistently (a token mixing +// with -/_ is
rejected), and have a valid Base64 length. On top of that, the decoded bytes
must look like real content — at least ~85% printable text, or a recognized
file signature. Short tokens and blobs that decode to random bytes are
deliberately skipped to avoid false positives.
Does it handle URL-safe Base64 and missing padding?
Yes. Both the standard (+//) and URL-safe (-/_) alphabets are decoded,
and trailing = padding is optional — the alphabet is picked per token based
on which marker characters it contains.
What do I get for a binary blob like an embedded image?
Instead of garbled text you get the detected file type (e.g. image/png,
application/pdf) sniffed from the magic bytes, the decoded byte count, and a
hex preview of the first 32 bytes. A binary blob whose format isn't recognized
is treated as noise and not reported.
Can I paste a whole JWT?
Yes — the dots between segments split the token naturally, so the header and payload decode as readable JSON (they're URL-safe Base64). The signature segment is random-looking bytes with no known file signature, so it's usually filtered out rather than shown as garbage.
Developer & Automation Access
Run it from the terminal
Same engine as this page, headless — via the gizza CLI:
gizza tool extract-decode-base64 "Paste text containing Base64, e.g. token=SGVsbG8sIHdvcmxkIQ=="New to the CLI? Get gizza →
Open it by URL
Pre-fill and auto-run this tool with query parameters — the names match the API/CLI:
https://gizza.ai/tools/extract-decode-base64/?text=Paste%20text%20containing%20Base64%2C%20e.g.%20token%3DSGVsbG8sIHdvcmxkIQ%3D%3DMachine-readable descriptor: tool.json — title + parameters JSON Schema for agents.