Base64 Encoder & Decoder
Convert Unicode text to standard Base64 or Base64url and inspect UTF-8 text encoded in either format.
Maximum 500,000 characters. Use synthetic examples instead of secrets.
Local processing · No account · Input is not uploaded by this tool
How to use this tool
- Choose the relevant options. Set the operation, format or algorithm before running. The options above define how the result is interpreted.
- Enter data or load an example. Hello, developer! Xin chào 👋
- Run and inspect the feedback. Use the primary action, then read the status message. An error clears old output so it cannot be mistaken for a fresh result.
- Copy, download or start again. Copy and Download become available when a current nonempty result exists. Reset clears the text result; no input is stored by this site.
How it works
TextEncoder creates UTF-8 bytes before btoa. Decoding restores bytes with atob and validates them using fatal UTF-8 TextDecoder. URL-safe mode replaces the alphabet and omits output padding.
The computation is performed by this page’s JavaScript after you choose Run. Input and results are kept in the current tab’s memory. There is no background submission, analytics event containing your input, or server-side conversion in this build.
Practical example
Use Load example to try the supported format, then change one value and run again. Comparing those two results is a quick way to understand what the operation changes and what it preserves. The linked guides below provide worked examples for the edge cases relevant to this utility.
Common mistakes
Base64 is reversible encoding, not encryption. Select the correct variant; decoding a token payload does not verify its signature.
Limits and unsupported tasks
This is a text tool, not a binary file decoder. Valid Base64 holding non-UTF-8 bytes causes an error. Whitespace in encoded input is ignored. Structurally valid unpadded input is accepted. Maximum input: 500,000 characters.
Privacy and handling sensitive data
Encoded text can still contain recoverable secrets. Use synthetic token segments and keep decoded private information out of screenshots. The UTF-8 and Base64 conversions happen in this tab, without a decoding service or stored history. Copy and Download use your device. Browser extensions and hosting logs have separate boundaries, explained in the privacy policy.
Usage guides
Questions, answered
Does the Base64 Encoder & Decoder upload my input?
No. The implementation processes it in your browser and does not submit it to a server. Ordinary page requests still reach the hosting service.
Why did Copy or Download become unavailable?
The input changed or validation failed, so the previous output was cleared. Run the tool again to create a current result.
Can I use this for every production workflow?
This is a text tool, not a binary file decoder. Valid Base64 holding non-UTF-8 bytes causes an error. Whitespace in encoded input is ignored. Structurally valid unpadded input is accepted. Maximum input: 500,000 characters.