Base64 Encoder & Decoder Online — Encode/Decode Text & Files
Enter any text in the input and the tool encodes it to Base64 in real time, or paste a Base64 string and toggle to decode mode to recover the original bytes. UTF-8 is fully handled, so multi-byte characters (emoji, accented letters, CJK) round-trip correctly through the Web API TextEncoder/TextDecoder bridge — not the naive btoa/atob that corrupts anything above code point 255.
This is the tool for decoding the payload or signature half of a JWT to inspect its claims, preparing a small inline image as a data URL, reading a Base64-encoded secret from a Kubernetes manifest, decoding an HTTP Basic auth header, generating the body of a data:image/png;base64,... URL, or producing Base64 strings for email attachment experiments and API test fixtures.
URL-safe Base64 is supported for values that travel in query strings or path segments: the variant uses - and _ in place of + and /, and padding = can be omitted. A one-click swap flips the direction so you can chain encode-then-decode to validate a round-trip, and the result can be copied to the clipboard without reformatting. Large inputs stream through incrementally so multi-megabyte text does not stall the UI.
All encoding and decoding runs client-side through browser APIs — your input never leaves the tab.
About this tool
Base64 is a binary-to-text encoding scheme that represents binary data as ASCII characters. It's commonly used in data URLs, email attachments, and API payloads.
- Real-time encode and decode
- Full UTF-8 support
- One-click swap between modes
- Copy result to clipboard
100% client-side. Your inputs never leave your browser. Ads via AdSense (consent required).
Frequently asked questions
How do I encode or decode base64?
Paste text or upload a file, pick encode or decode, and the tool runs the operation instantly. Encode converts text to base64 using UTF-8 by default; decode accepts both standard and URL-safe base64 (with - and _ instead of + and /) and auto-detects padding. For files, encoding produces a base64 string you can embed in data URLs or HTTP payloads; decoding a base64 string produces a downloadable binary.
Is the base64 tool free?
Yes, fully free with no signup. Encode and decode unlimited text or files, any size your browser can hold in memory. JSONCraft has a single open tier across every tool; base64 is as unrestricted as the JSON formatter and converters. Useful for data URLs, JWTs, HTTP basic auth and email MIME payloads.
Does the base64 tool upload my data?
No. All encoding and decoding happen in your browser. File uploads go through the FileReader API locally; text input never leaves the page. This is crucial for base64-encoded secrets — JWTs, API keys, certificate payloads — where you absolutely don't want the raw value hitting a third-party server.
What's the difference between standard and URL-safe base64?
Standard base64 uses + and / and = padding, which breaks in URLs and filenames (they have reserved meanings). URL-safe base64 (RFC 4648 section 5) replaces + with - and / with _ and often drops padding. The tool encodes to standard by default with a toggle for URL-safe; the decoder auto-detects both so you can paste any variant.
How does charset handling work for non-ASCII text?
Text is encoded as UTF-8 before base64, which is the modern standard. So encoding 'café' produces 'Y2Fmw6k=' (UTF-8 bytes), not a latin-1 variant. Decoding reverses this: base64 bytes are interpreted as UTF-8 text by default. If your input is known to be a different charset (rare today), decode as binary and convert the bytes yourself.