Convert any text to a Base64-encoded string or decode a Base64 string back to its original text. Useful for encoding data for APIs, email attachments, and data URIs.
Workspace
Use the tool below. Your inputs stay local when the tool supports browser-only processing.
Last reviewed: · Testing methodology
Workflow
Type your plain text directly into the input area or paste Base64-encoded strings that you want to decode. This Base64 encoder/decoder tool accepts standard text input as well as binary data representations, making it easy to encode data for use in data URIs or API payloads.
Choose the encode option to convert your plain text into a Base64 string, or select decode if you have a Base64 string that needs to be turned back into readable text. The Base64 encoder/decoder performs the conversion in real time so you can see the result instantly.
Copy the generated Base64 string or decoded text with a single click. Developers commonly use a Base64 encoder/decoder to embed small images directly in HTML and CSS and to transmit binary data safely through text-based protocols like JSON and XML.
The component converts UTF-8 bytes to the Base64 alphabet or reverses that representation locally.
Use it for data URIs, API test values, and inspecting small payloads. Never treat Base64 as protection for secrets.
Use command-line utilities or streaming code for large files, pipelines, checksums, encryption, or repeatable automation.
| Option | Best for | Trade-off |
|---|---|---|
| This browser tool | Quick, private, one-off work | Limited by browser memory and the documented feature set |
| Desktop or command-line tool | Batch jobs and repeatable automation | Requires installation and setup |
Reviewed by the Free Online Tools Nest Team on 2026-08-26. The interface, output path, and documented limitations were checked against the current implementation. See our testing methodology for the review process.
Read the testing methodologyA Base64 encoder/decoder allows binary data such as images, audio files, or document blobs to be represented as plain ASCII text that can travel through systems designed for textual data. When you encode with this Base64 encoder/decoder tool, you produce a string that can be safely embedded in JSON responses, HTML attributes, or CSS background-image properties without corruption.
Yes — Base64 encoding increases the data size by approximately 33 percent because every three bytes of binary data are represented as four ASCII characters. This overhead is a worthwhile trade-off when you use a Base64 encoder/decoder for secure text-based transport, but you should avoid it for very large files if bandwidth is a concern.