Base64 Encode

Runs 100% in your browser

Encode UTF-8 text and local files to standard or URL-safe Base64 with optional padding, line wrapping, Data URI prefixes, byte statistics, and browser-only processing.

Developer encoding utility

Encode and decode Base64 locally

Work with UTF-8 text, API payloads, data URIs, and local files without sending data to a server. Base64 is an encoding—not encryption.

Local only

Step 1

Input

Ready

0 bytesUTF-8 text

Step 2

Encoding settings

Standard Base64

AlphabetLine wrappingPaddingData URI MIME type

Ignore whitespace while decodingStrict validation for malformed Base64Preserve bytes when encoding a local file

Step 3

Output

Waiting for input

0 bytesNo output yet

At a glance

Encoding statistics

Input bytes0

Output characters0

Expansion—

AlphabetStandard

Padding—

Line count0

Private by architecture

Text and local files are processed with browser-native APIs. No fetch, upload, server-side conversion, or persistent history is used. Base64 only changes representation; it does not protect secrets like encryption.

Session only

Recent conversions

Recent conversions disappear when this page closes.

Frequently asked questions

What is Base64 encoding?

Base64 is a binary-to-text encoding that represents bytes with a 64-character alphabet using letters, numbers, plus, slash, and optional equals padding. It makes binary data safe to carry through text-oriented formats such as email, JSON, and HTTP headers, but it is not encryption.

How do I encode text to Base64?

Paste UTF-8 text into the encoder and the tool converts it into UTF-8 bytes, maps those bytes to Base64 characters, and displays the result. Unicode, accented characters, and emoji are all supported because encoding starts from the UTF-8 byte sequence.

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

Standard Base64 uses + and / in its alphabet. URL-safe Base64 replaces them with - and _ so the output is safe inside URL parameters, filenames, cookies, and tokens where + and / have special meanings. Some systems also strip trailing = padding.

Can I create a Base64 Data URI for an image or SVG?

Yes. Select a MIME type such as image/png, image/svg+xml, text/plain, application/json, or application/octet-stream and the encoder prepends a data:MIME;base64, prefix. Paste the result directly into an HTML src or CSS url() field.

Can Base64 encode a local file without uploading it?

Yes. Switch to the Local file input, choose a file from your device, and the browser reads its bytes locally using FileReader. The file is never sent to a server. For images, PDFs, and binaries the output can be used as a Data URI or API payload.

Does Base64 encoding make a file larger or smaller?

Larger. Every three input bytes become four Base64 characters, so the output is roughly 33% bigger before any line wrapping or prefix is added. Base64 improves text-transport compatibility, not file size. Compress data separately when the protocol allows it.

What does the equals sign at the end of Base64 mean?

The = characters are padding added so the encoded output fills complete four-character groups. Decoders can usually restore missing padding automatically, but keep it when the receiving API or protocol requires canonical Base64.

What is line wrapping in Base64 and when do I need it?

Line wrapping breaks the output into fixed-width lines. MIME email uses 76 characters, PEM certificates use 64 characters. Without wrapping the output is one long string, which is what most JSON APIs and token fields expect. Choose the width that matches your target format.

Is Base64 encoding the same as encryption?

No. Base64 is reversible encoding and provides no confidentiality. Anyone who holds the output can decode it with any Base64 decoder. Use authenticated encryption or a secure transport layer when data must remain secret.

Is this Base64 encoder private and safe to use?

The encoder uses browser-native TextEncoder and the btoa function for text, and FileReader for local files. It does not call a conversion API, upload input to a server, or save conversion history in localStorage. Avoid pasting private credentials on shared or public devices.

How do I convert an image or file to Base64?

Switch to file mode and pick the file. It is read locally with the FileReader API and encoded in your browser — nothing is uploaded. You can copy the result or a ready-made data URI.

What is a data URI and when should I use one?

A data URI embeds a Base64-encoded file directly in HTML or CSS, for example data:image/png;base64,... It is handy for small icons and email images where separate file requests are impractical.

Does the encoder handle Unicode text correctly?

Yes. Text is encoded as UTF-8 first, so emoji and non-Latin characters round-trip correctly when decoded with a UTF-8 aware decoder.

What is the URL-safe Base64 variant?

Standard Base64 uses + and / characters, which clash with URLs. The URL-safe variant (RFC 4648) replaces them with - and _ so the encoded value can travel in links, filenames, and JWT segments. The tool supports both.

Is Base64 encryption?

No. Base64 is an encoding, not encryption — anyone can decode it. Use it for transport and embedding, never for protecting secrets.

Why does Base64 make my data about 33% bigger?

Base64 represents every 3 bytes of input as 4 output characters, so the encoded form is roughly a third larger. That is the price of making binary data safe for text-only channels.

Can I encode large files?

Yes, within your browser memory. Because encoding is local there is no server file-size quota or rate limit.

Is my content private when encoding?

Everything runs locally in your browser with no upload, no account, and no logging. You can confirm in your browser DevTools Network tab that no request carries your data.

What is Base64 Encode?

Base64 encoding is a binary-to-text scheme that converts any sequence of bytes into a string of printable ASCII characters using a 64-character alphabet: A–Z, a–z, 0–9, plus (+), slash (/), and optional equals (=) padding. Every three input bytes map to four output characters, making the encoded result about 33 percent larger than the original. Despite the size increase, Base64 is ubiquitous in software because it makes binary data safe to carry through channels that only accept text.

The most common uses of Base64 encoding include MIME email attachments, where binary files must travel through text-only SMTP servers; inline data URIs in HTML and CSS that embed small images, fonts, or SVGs without a separate HTTP request; HTTP Basic Authentication headers that encode a username:password pair; JSON API payloads that need to transmit binary blobs; JWT (JSON Web Token) header and payload segments; PEM certificate files; and environment variables or configuration fixtures that must hold binary values as plain text.

Standard vs URL-safe Base64

Standard Base64 uses + and / as its 62nd and 63rd characters. These are safe in email and most APIs, but they cause problems inside URL query parameters and filenames where + means a space and / is a path separator. URL-safe Base64 (also called Base64url) replaces + with - and / with _ so the output can appear in a URL without percent-encoding. JWTs, OAuth tokens, file identifiers, and browser cookie values commonly use the URL-safe alphabet. Some systems also strip trailing = padding to keep the string even shorter.

Line wrapping

Older formats specify a maximum line length for Base64. MIME and email systems traditionally wrap at 76 characters (RFC 2045). PEM headers, certificate files, and SSH keys typically wrap at 64 characters. Modern JSON APIs, token fields, and database columns expect a single continuous string with no line breaks. ToolsSonic's encoder lets you choose no wrapping, 64, 76, 80, or 100 characters so your output matches whatever receiving system you are targeting.

Data URI output

A Data URI packs a Base64-encoded file directly into a markup or stylesheet attribute so the browser does not need to make a separate network request for that asset. The format is data:MIME-type;base64,<encoded-bytes>. Selecting a MIME type in the encoder automatically prepends the correct prefix. Typical use cases include small icons in CSS background-image, inline SVG in HTML img src, and base64-encoded JSON payloads in API test fixtures.

Encoding files without uploading

ToolsSonic's encoder accepts local files through the browser's FileReader API. The file is read into an ArrayBuffer entirely in your browser and never transmitted to a server. This makes it safe to encode sensitive configuration files, private keys, and personal documents while still getting the Base64 output you need for your workflow.

Why ToolsSonic Base64 Encoder outranks competitors

Base64encode.org and similar tools offer a plain textarea with a single Convert button. ToolsSonic's encoder adds alphabet selection (standard or URL-safe), configurable padding, five line-wrap widths, six Data URI MIME types, local file encoding, live preview, byte-to-character expansion statistics, clipboard paste, one-click copy, file download, session history, and a clear privacy statement — all without requiring a server round-trip or account.

Common use cases

Encoding API credentials for HTTP Basic Auth headers
Embedding a small icon as a CSS data URI without a server request
Encoding a local PDF or image for an API payload
Generating URL-safe Base64 tokens for cookies and filenames
Creating MIME-wrapped Base64 for email attachments
Wrapping at 64 characters for PEM certificate generation

Why use ToolsSonic's Base64 Encode?

ToolsSonic's Base64 Encoder supports standard and URL-safe alphabets, padding keep/remove, five line-wrap widths, six Data URI MIME prefixes, local file encoding via FileReader, live preview, byte expansion statistics, clipboard paste, one-click copy, file download, and session-only history. It processes everything in your browser with no server calls — making it the most capable private Base64 encoder available online.

100% private — runs in your browser Instant — no server round-trip Free forever — no account needed

Base64 Decode

Decode standard or URL-safe Base64 back to UTF-8 text locally. Handles Data URI prefixes, whitespace, missing padding, strict validation, malformed input errors, and readable output statistics.