Base64 Decode Online - Free, No Sign-Up
Overview
Base64-encoded strings appear in JWT payloads, email MIME parts, HTTP Basic Auth headers, and data URIs. Paste the encoded string and the decoder outputs the original text. URL-safe Base64 uses - and _ instead of + and /, which the decoder handles automatically without any mode switch.
How to Use This Tool
Paste the Base64 string into the input field. The decoded output appears instantly. If the string is URL-safe (contains - or _), the decoder normalises it automatically. For binary data decoded as garbled text, try downloading the output as a raw file instead.
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PDF Tool →Frequently Asked Questions
What is the difference between standard Base64 and URL-safe Base64?
Standard Base64 uses + and / in its character set, which are special characters in URLs and query strings. URL-safe Base64 (Base64url) replaces + with - and / with _ so the string is safe to use in URLs without percent-encoding.
Why do I see garbage characters when decoding?
The decoded bytes may represent binary data rather than plain text. This happens when decoding images, PDFs, or other binary files encoded in Base64. Use a download option to save the raw bytes rather than reading them as text.
Can I decode the payload of a JWT with this tool?
Yes. Copy the middle segment of the JWT (between the first and second dot) and paste it here. The decoder handles Base64url without padding automatically and outputs the JSON payload.