Debug URL-safe Base64 strings with missing padding

Inspect Base64 values that use dash and underscore substitutions or omit padding characters in URLs and tokens.

URL-safe Base64 appears often in web tokens and query strings. It looks close to standard Base64, but small differences can break decoding if you do not account for them.

Open the tool Expected result

How to use it

Step 1

Identify URL-safe characters

Look for dash and underscore replacements that indicate the URL-safe variant.

Step 2

Normalize before decoding

Restore standard characters or padding as required by your workflow.

Step 3

Verify the decoded payload

Check that the text output matches the JSON or token claims you expected.

Sample input

eyJmbGFnIjp0cnVlfQ

Expected result

You can separate formatting problems from actual payload errors when a token-like string refuses to decode cleanly.

Common mistakes

Treating a URL-safe value as standard Base64 without conversion.
Ignoring absent padding.
Assuming every token segment is meant to be human-readable.

Related workflows

Decode a Base64 API token payload for inspection

Guide

Encode a small image or SVG snippet into Base64

Guide

Related tools

Decode JSON Web Tokens

ToolsDashboard

debug url safe base64

Debug URL-safe Base64 strings with missing padding

Inspect Base64 values that use dash and underscore substitutions or omit padding characters in URLs and tokens.

URL-safe Base64 appears often in web tokens and query strings. It looks close to standard Base64, but small differences can break decoding if you do not account for them.

Open the tool Expected result