Base64 Encoder & Decoder
Encode text or files to Base64, or decode Base64 back to text. Supports URL-safe variant. Everything runs in your browser — nothing is sent to any server.
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What is Base64 Encoding?
Base64 is a binary-to-text encoding scheme that represents binary data as a sequence of printable ASCII characters. It is widely used in web development and data transmission.
Common Use Cases
- Email attachments — MIME encoding for sending binary files over text-based email protocols
- Data URIs — Embedding images directly in HTML or CSS using
data:URLs - API payloads — Transmitting binary data within JSON payloads
- Authentication — HTTP Basic Authentication encodes credentials in Base64
- Cookies & URLs — Storing complex data structures in cookies or query parameters
The API-payload case is the one that trips people up in AI work. OpenAI’s Realtime API will not take a raw audio stream: it expects PCM16 chunks at 24 kHz, Base64-encoded, pushed as input_audio_buffer.append events. That is why building a voice agent on that API begins with a browser-side format conversion rather than a microphone handle. Decoding a captured chunk here is a fast way to confirm you encoded the bytes you meant to before blaming the model.
Standard vs URL-safe Base64
Standard Base64 uses A-Z, a-z, 0-9, +, and / with = padding. URL-safe Base64 replaces + with - and / with _, and removes padding. This makes it safe for URLs and filenames.
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