Free Online Base64 Encoder / Decoder
Encode any text string to Base64 or decode a Base64 string back to plain text. Full Unicode support — works with emojis, accented characters, and multi-byte scripts.
What is Base64?
Base64 is an encoding scheme that converts binary data — or any text — into a string of 64 printable ASCII characters (A–Z, a–z, 0–9, +, /). It is widely used wherever binary data needs to be safely transmitted through text-based channels such as HTTP headers, JSON payloads, or email attachments.
Base64 is not encryption. The original data can be recovered by anyone with the encoded string. Use it for encoding, not for securing sensitive information.
How to Use the Base64 Tool
- Select the mode — Encode to convert text → Base64, or Decode to convert Base64 → text.
- Paste your input into the left field.
- Click Encode / Decode to process. The result appears on the right.
- Use Swap to flip the output back into the input field and switch modes — handy for round-trip testing.
Common Use Cases
- API authentication: Basic Auth credentials are sent as Base64-encoded
username:passwordin the Authorization header. - JWT tokens: Decode the header and payload sections of a JWT to inspect claims without a dedicated library.
- Image embedding: Inline small images in CSS or HTML as Base64 data URIs to reduce HTTP requests.
- Email attachments: MIME encodes binary attachments as Base64 so they can travel safely through mail servers.
Frequently Asked Questions
No. Base64 just re-represents data using a different character set — anyone can decode it back to the original with no key or password needed. If you need to keep data secret, use actual encryption; Base64 is only for safely transmitting data through text-only channels.
Base64 encodes every 3 bytes of input as 4 output characters, so the encoded string is roughly 33% larger than the original. This overhead is the trade-off for representing arbitrary binary data using only safe, printable ASCII characters.
Yes. Text is encoded as UTF-8 before Base64 conversion, so accented characters, emoji, and multi-byte scripts (Cyrillic, CJK, etc.) round-trip correctly through encode and decode.
Yes, the decoder tolerates whitespace and line breaks commonly found in Base64 blocks copied from emails or config files, stripping them before decoding.
It's completely free with no limits, and nothing is sent anywhere — encoding and decoding happen entirely in your browser using JavaScript.