Frequently Asked Questions
Everything you need to know about the Base64 Encoder / Decoder.
How does the Base64 Encoder / Decoder work?
Paste text in the Plain text field to encode it to Base64, or paste Base64 in the right field to decode it back to text. Either field updates the other instantly as you type — no button needed.
Is this Base64 tool free?
Completely free. No sign-up, no download, no rate limits, no limits on input length.
What is Base64?
Base64 is an encoding scheme that represents binary data or arbitrary text as a string of ASCII characters using an alphabet of 64 symbols (A–Z, a–z, 0–9, +, /). It is widely used to transmit binary data in text-only contexts such as JSON payloads, email attachments (MIME), data URIs, and HTTP Basic Auth headers.
Does it handle emoji and accented characters correctly?
Yes. The tool encodes text to UTF-8 bytes first using the TextEncoder API, then converts to Base64 — so emoji, accented letters, and non-Latin scripts all round-trip correctly. Browsers' built-in btoa() and atob() are limited to Latin-1 and corrupt these characters; this tool avoids that problem entirely.
What is URL-safe Base64?
Standard Base64 uses + and / characters, which have special meaning in URLs and must be percent-encoded. URL-safe Base64 replaces + with - and / with _ so the result can be placed directly in a URL, filename, or HTTP header without further encoding. Toggle "URL-safe" to switch. The decoder accepts both variants automatically.
What does "No padding" mean?
Standard Base64 output is padded with = characters to make the length a multiple of 4. Some systems (JWT, for example) strip this padding. Toggle "No padding" to omit the = characters from the encoded output. The decoder handles unpadded input automatically by restoring the padding before decoding.
Can I encode a file to Base64?
Yes. Switch to the File tab, drop a file or click to browse, and the tool encodes it to a Base64 data URI in your browser. You can copy the full data URI (useful for embedding images in HTML or CSS) or just the raw Base64 string. No file is uploaded anywhere.
Why am I getting a decode error?
The input is not valid Base64. Common causes: invalid characters (only A–Z, a–z, 0–9, +, /, =, -, _ are allowed), incorrect length (Base64 without padding must be a length divisible by 4 after padding is restored), or corrupted data. The error message tells you exactly what is wrong.
Is my data sent to a server?
No. All encoding and decoding happens entirely in your browser using JavaScript. Nothing is sent to any server, so sensitive strings like API keys, tokens, or credentials stay on your device.
Does it work on mobile?
Yes. The layout is fully responsive. On small screens the two fields stack vertically so both are easy to read and interact with. All features — encoding, decoding, URL-safe, file mode — work on mobile browsers.