How is UTF-8 / Chinese handled?

JavaScript's built-in btoa() only accepts Latin-1 bytes, so naively passing a Chinese string to it throws a character out of range error. This tool first runs the text through TextEncoder("utf-8") to get a proper byte array, then converts each byte to its char code with String.fromCharCode, and finally feeds that to btoa. Decoding reverses the process with atob + TextDecoder. This means any valid Unicode — Chinese characters, Japanese, Arabic, emoji — round-trips correctly.

What is the difference between a Data URL and raw Base64?

Raw Base64 is just the encoded bytes: "aGVsbG8=". A Data URL wraps that in a URI scheme that browsers can interpret directly: "data:text/plain;base64,aGVsbG8=". You can use a Data URL as the src of an tag, a CSS background-image, or a download link — without hosting the file anywhere. The toggle in this tool prepends the MIME type prefix automatically when you encode a file.

What is the difference between URL-safe Base64 and standard Base64?

Standard Base64 uses + and / as its 62nd and 63rd characters, and = for padding. Those characters have special meaning in URLs, so if you embed a standard Base64 string in a query parameter you must percent-encode it. URL-safe Base64 (RFC 4648 §5) swaps + → -, / → _, and drops the = padding, making the output safe to place directly in a URL path or query string without any escaping. Use standard mode for file encoding and data storage; use URL-safe mode for tokens, JWTs, and URL parameters.

Base64 Encoder & Decoder

Encode or decode Base64 — text, files, and Data URLs. Runs entirely in your browser.

Runs locally
Category Encoding & Crypto
Best for Checking file type, size, metadata, and obvious mismatch signals before sharing.

URL-safe

Input

Output

What this tool does

A clean, privacy-first Base64 tool. Paste text or drop a file to encode it, or paste a Base64 string to decode it back. Handles UTF-8 correctly (Chinese, emoji, anything Unicode), supports URL-safe mode, and can wrap output in a Data URL prefix for use in CSS or HTML. Your data never leaves the browser.

Tool details

Input: Files + Text + Structured content; The page exposes text boxes, numeric controls, file pickers, or structured inputs depending on the tool.
Output: Live result + Copy + Download; The result area focuses on usable output, with copy, download, or preview actions when supported.
Privacy: Browser-side processing; The main tool logic does not call an external API, so inputs normally stay in the current tab.
Save / share: Shareable URL state; Key settings are encoded in the URL so another person can reopen the same setup.
Performance budget: Initial JS <= 20 KB; No WASM budget is declared, keeping the tool quick to open on mobile.
Best fit: Encoding & Crypto · Developer; Category and role tags drive related tools, internal links, and quick fit checks.

How to use

1. Input

Paste or drop your content into the tool panel.
2. Process

Click the button. All processing is local in your browser.
3. Copy / Download

Copy the result or download to disk in one click.

How Base64 Encoder & Decoder fits into your work

Use it before upload, handoff, archive, support review, or any moment where a file needs one local check before it leaves your machine.

File jobs

Checking file type, size, metadata, and obvious mismatch signals before sharing.
Preparing mixed folders for upload, archive, intake, or review.
Keeping sensitive files in the browser instead of sending them to an account-based service.

File checks

Do not treat the extension alone as proof of the real file type.
Review metadata before a file goes to customers, vendors, or a public page.
Keep the original file until the copied, converted, or exported result is verified.

Good next steps

These links move the current task into a more complete workflow.

FAQ

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Base64 Encoder & Decoder

What this tool does

Tool details

How to use

1. Input

2. Process

3. Copy / Download

How Base64 Encoder & Decoder fits into your work

File jobs

File checks

Good next steps

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