Base64 to ASCII

Decode a Base64 string back to its original ASCII text. Ideal for reading HTTP Basic Auth headers, inspecting encoded API tokens, and debugging configuration values that were Base64-encoded before storage.

Last updated: May 28, 2026

Base64 input

URL-safe(converts - _ back to + /)

ASCII output

Tip: To read an HTTP Basic Auth header, copy the value after Basic and decode it here. The result will be username:password. Enable URL-safe mode for JWT payload sections.

Client-Side Processing

Input Data Stays on Device

Instant Local Execution

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What is Base64 to ASCII?

Base64 to ASCII decoding reverses the encoding process: it takes the 64-character ASCII representation and recovers the original bytes as readable text. This operation is essential when debugging authentication headers, inspecting JWT payloads (the header and payload sections are Base64url-encoded), and reading encoded config values from environment files.

ASCII is the 128-character range covering English letters, digits, and standard punctuation. When a Base64 string encodes ASCII content, decoding it produces clean, readable text without any binary garbage. This tool makes that process one click.

How to Use Base64 to ASCII

Paste the Base64 string into the input field

Click "Decode to ASCII" to recover the original text

Enable URL-safe mode if the string uses - and _ instead of + and /

Copy the decoded result with the copy button

Common Use Cases

Developers decoding the Authorization header value to read the username:password credential block.
Engineers inspecting Base64-encoded API tokens to verify the payload matches expectations.
Security analysts decoding encoded strings found in logs, config files, or network captures.
QA testers checking that an ASCII payload encodes and decodes correctly through a round trip.
DevOps engineers reading Base64-encoded Kubernetes secrets or environment variable values.

Example Input and Output

Decoding an HTTP Basic Auth header credential block back to the original username:password pair.

Base64 string

ZGVwbG95LWJvdDpnaF90b2tlbl9hYmMxMjNYWVo=

ASCII output

deploy-bot:gh_token_abc123XYZ

Always use HTTPS

Base64-encoded credentials in Authorization headers are trivially reversible. Always use HTTPS so headers are encrypted in transit.

JWT payloads

JWT payloads use Base64url encoding (URL-safe variant, no padding). Enable URL-safe mode and paste the middle segment (between the two dots) to inspect the payload.

Frequently Asked Questions

How do I decode an HTTP Basic Auth header?

Copy the Base64 value after "Basic " in the Authorization header, paste it here, and click Decode. The result will be "username:password".

What if my Base64 string ends without = padding?

Some systems strip the trailing = padding. If you get an invalid Base64 error, try appending one or two = characters to the end of the string and decode again.

What is URL-safe Base64?

URL-safe Base64 uses - instead of + and _ instead of / so the string can appear in URLs without percent-encoding. Enable URL-safe mode if your string contains those characters.

Can I decode Base64 that encodes binary or UTF-8 data?

This tool decodes Base64 and displays the result as text. If the original data was binary, the output may contain unreadable characters. For UTF-8 encoded content, use the Base64 to Text tool instead.

Is my data sent to a server?

No. Decoding runs entirely in your browser. Nothing is transmitted.