1. What does this tool do
This free online Base64 encoder decoder converts text to Base64 and Base64 back to plain text. Use it for Base64 encode, Base64 decode, or Base64 encoding in APIs, data URLs, or configs. Paste or type your input and get the result instantly—no sign-up, no upload. UTF-8 is supported so international characters encode and decode correctly. All processing runs in your browser. Ideal for APIs, data URLs, logs, or encoding checks.
2. How to use it
Quick start: Choose Encode or Decode, paste text or Base64, then view and copy the result. Invalid Base64 shows an error when decoding.
- Choose mode — Select Encode (text → Base64) or Decode (Base64 → text).
- Enter input — Paste or type text to encode, or Base64 to decode.
- View result — The output appears in the other box. Invalid Base64 (when decoding) will show an error.
- Copy — Copy the encoded or decoded result for use in APIs, configs, or data URLs.
3. How it works
Encode: The input string is converted to UTF-8 bytes, then encoded to Base64 (standard alphabet, with padding). Decode: The Base64 string is decoded to bytes and interpreted as UTF-8 text. The browser’s atob/btoa or a small library may be used; UTF-8 text is often handled via encodeURIComponent/decodeURIComponent or a dedicated routine. All processing is client-side in your browser. No data is sent to any server.
4. Use cases & examples
- APIs — Encode credentials or small payloads for headers or JSON.
- Data URLs — Encode an image or small file as Base64 for embedding.
- Logs or config — Decode Base64 strings found in logs or configs.
- Encoding check — Verify that a string round-trips correctly with UTF-8.
Example
- “Hello” → encode → “SGVsbG8=”. Decode “SGVsbG8=” → “Hello”.
- “Café” (UTF-8) → encode → Base64 string. Decode that → “Café”.
5. Limitations & known constraints
- Text focus — The UI is best for text. Very large binary data may be slow or impractical in a text area.
- Padding — Standard Base64 uses padding (=). Some systems omit it; the tool may or may not accept padding-less input depending on implementation.
- URL-safe — Standard Base64 uses + and /. For URL-safe encoding (e.g. - and _), the tool may offer a separate option if implemented.