CONVERTERS
Base64 Encoder/Decoder
Encode text to Base64 or decode Base64 back to text.
UTF-8 READY
Convert text locally
Your text is converted in the browser and is never uploaded.
Base64 encoder/decoder guide
Base64 is a way to represent binary data using only 64 printable ASCII characters (A–Z, a–z, 0–9, +, /, and = for padding). It is everywhere: email attachments, data URLs in HTML, JSON payloads, JWTs, and API authentication.
This tool encodes and decodes Base64 with full UTF-8 support, right in your browser. Nothing is uploaded — the conversion happens locally on your device.
Why Base64 exists
Many protocols and formats were designed for text, not raw bytes. Emails historically allowed only 7-bit ASCII; JSON and XML have no native binary type; URLs cannot contain arbitrary bytes. Base64 solves this by encoding any binary data as safe, printable text.
The cost is size: Base64 expands data by about 33%. Three bytes become four characters. That is fine for small payloads and the reason it is used everywhere — and also a reason to avoid it for large files.
Common uses
- Data URLs — embedding small images directly in HTML or CSS: data:image/png;base64,iVBORw0KGgo….
- JWT tokens — the header and payload of JSON Web Tokens are Base64url-encoded JSON.
- Email attachments — MIME encoding wraps file attachments in Base64.
- API authentication — many APIs accept Basic auth as Base64(user:password).
- Storing binary in JSON or databases — when you must ship bytes through a text-only channel.
Base64 vs Base64url
Standard Base64 uses + and /, which have special meaning in URLs and filenames. Base64url swaps them for - and _ and drops the = padding, producing strings that are safe in URLs without escaping.
JWTs and many web APIs use Base64url. If you decode something that looks like Base64 but contains - or _, that is what you are looking at. This tool handles both when decoding.
Is Base64 encryption?
No. Base64 is an encoding, not encryption. It is trivially reversible — anyone can decode it, including your browser in the click of a button. Treat Base64 as obfuscation at best: never use it to protect secrets, passwords, or sensitive data.
If you need to hide data, use real encryption (AES). And if you are sending Base64 over a network, always do it over HTTPS — otherwise the payload is readable in transit.
Frequently asked questions
What is Base64 used for?
Representing binary data as safe ASCII text for transmission through text-only channels: email attachments, JSON payloads, data URLs, JWTs, and API authentication.
Is Base64 the same as encryption?
No. Base64 is an encoding that anyone can reverse instantly. It obscures data but provides zero security.
Why does Base64 output end with = signs?
The = characters are padding. Base64 encodes data in 3-byte groups; when the input length is not a multiple of 3, one or two = signs pad the output to a multiple of 4 characters.
Does Base64 increase file size?
Yes — by about 33%. Three input bytes become four Base64 characters. This is why Base64 is a poor choice for large files.
What is the difference between Base64 and Base64url?
Base64url replaces + and / with - and _ and omits padding, making the output safe for URLs and filenames. JWTs use Base64url.
Why is my decoded text showing garbled characters?
The input may not be valid Base64, or it may encode binary data (images, compressed files) rather than text. Try decoding it as UTF-8 only if it is genuinely text.
Privacy note: Base64 conversion happens in your browser. Your input is not submitted to NAB Tools.