DecoderBase64
Decode Base64-encoded strings back into their original plain text instantly with this free online tool. Base64 strings are common in JWT tokens, HTTP Authorization headers, API responses, configuration files, email headers, and data URIs. When you encounter a Base64-encoded value and need to inspect its contents, this decoder reveals the original data immediately without needing to write code or use command line tools.
Use Base64 Tool in Seconds
Base64 Decoder
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How To Use Base64 Decoder
- Paste the Base64-encoded string into the input field.
- The tool applies Base64 decoding to the input and reconstructs the original byte sequence.
- The decoded plain text output is displayed immediately in the result area.
- Review the decoded content to inspect the original data value.
- Copy the decoded result for use in debugging, analysis, or documentation.
Frequently Asked Questions
Can this decode Base64 strings back to plain text?
Yes. The decoder reverses the Base64 encoding process and returns the original plain text string. For example, 'SGVsbG8gV29ybGQ=' decodes to 'Hello World'. The decoder handles standard Base64 including the padding characters (=) that appear at the end of encoded strings.
How can I tell if a string is Base64 encoded?
Base64-encoded strings consist of letters (A–Z, a–z), numbers (0–9), plus signs (+), and forward slashes (/), often ending with one or two equals signs (=) as padding. The length is always a multiple of 4 characters. If you see a long alphanumeric string with occasional + and / characters ending in = signs, it is likely Base64. URL-safe Base64 uses - and _ instead of + and /.
Can I decode JWT tokens with this tool?
JWT tokens have three parts separated by dots — header, payload, and signature. The header and payload are Base64 URL-encoded JSON objects. You can decode each part separately by pasting the portion between dots (replacing - with + and _ with / if needed for standard Base64 compatibility). The decoded JSON reveals the token's claims and metadata. However, for dedicated JWT inspection with automatic handling, use the JWT Decoder tool on this site.
Why does the decoded output sometimes look like garbled characters?
If the original Base64 encoded binary data (like an image or PDF) rather than a text string, decoding it in a text tool produces garbled output because binary data is not valid UTF-8 text. Binary Base64 content should be decoded and processed as file data, not as a text string. This tool is best suited for Base64 that encodes text values like JSON, credentials, or plain strings.
What is the difference between Base64 decoding and URL decoding?
Base64 decoding converts a Base64-encoded alphanumeric string back to its original content. URL decoding converts percent-encoded sequences (%20, %26) in a URL back to the original characters. These are entirely different encoding schemes used in different contexts. For URL-encoded strings, use the URL Decoder tool on this site.
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