Input text / file
{{ inputBytes }} bytes in • {{ outputBytes }} bytes out (×{{ sizeRatio }})
Base64-encoded text
Recent Encodes
  • {{ h }}
Categories: Base64 , Encoder , Text
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Base64 Encoder swiftly transforms text or binary payloads into standards-compliant Base64, ensuring message integrity across e-mail, JSON, XML, and URL contexts that restrict raw bytes. By representing every three original bytes as four ASCII characters, it removes encoding ambiguity, streamlines content embedding, and prevents corruption during transit through systems that re-interpret or sanitize non-printable data.

The interface prioritises clarity and responsiveness: a single split card juxtaposes input and output textareas, augmented by drag-and-drop upload, byte counters, and persistent history. Visual cues emphasise mode selections such as URL-safe or padding suppression, while dark-mode toggling aligns with user preferences across desktops, tablets, and mobile devices without sacrificing readability or accessibility.

Behind the scenes the encoder runs entirely in the browser, eliminating server round-trips, protecting sensitive data, and delivering instantaneous feedback even on large files. Its clipboard integration, toast notifications, and keyboard shortcuts promote an uninterrupted workflow for developers, content authors, and security analysts who routinely embed resources in configuration files or data URIs.

Technical Details

The reference sheet below summarises functional capabilities, configuration switches, and illustrative output samples that optimise everyday use.

  • Browser-only processing keeps all content local for maximum privacy.
  • Drag-and-drop file import accepts binary sources up to 10 MB.
  • Live byte counters reveal input size, output size, and expansion ratio.
  • URL-safe toggle replaces +// with -/_ for query-string compatibility.
  • No-padding option removes trailing = when length constraints apply.
  • Persistent history stores up to ten recent encodings in localStorage.
  • Dark/Light themes adapt automatically or via a single switch.
  • Keyboard shortcut Ctrl + Enter copies the current output instantly.
Setting Icon Resulting Output
URL-safe Encodings contain - and _ instead of + and /.
No padding Trailing = characters are omitted, shortening the string.
History Most-recent ten encodings are available for one-click recall. 
Input  : Hello, world!
Encoded: SGVsbG8sIHdvcmxkIQ==

Step-by-Step Guide

Execute the following sequence to convert source data into a transport-ready Base64 string.

  1. Open Base64 Encoder and confirm the page title appears in the navbar.
  2. Click inside Input text / file and type or paste your content, or Caution drag-and-drop a file no larger than 10 MB.
  3. (Optional) Toggle URL-safe if the result will be embedded in URLs or cookies.
  4. (Optional) Activate No padding to remove trailing = symbols for strict-length channels.
  5. Observe the Base64-encoded text area populate instantly while byte counters update.
  6. Press Copy to clipboard or hit Ctrl + Enter Tip to copy the output and trigger a toast confirmation.

FAQ

The answers below resolve common functional and conceptual questions.

Why is the encoded string longer than the original input?

Base64 expands data by roughly 33 % because every three bytes become four ASCII characters. The increase is predictable and unavoidable.

What does the URL-safe option change?

It substitutes + with - and / with _, ensuring the output remains unescaped inside URLs, cookies, or filenames.

How can I decode Base64 back to its original form?

Use the matching decoder tool or run base64 --decode on most Unix-like systems. Ensure any URL-safe substitutions are reversed first.

Why do some outputs end with one or two = signs?

The padding characters align the final quantum to a four-byte boundary; they can be safely stripped when the receiver can restore them.

Does the encoder store or transmit my data?

No. All processing happens strictly in your browser memory; nothing is uploaded or logged beyond your device.

Troubleshooting

Refer to these resolutions when unexpected behaviour surfaces.

Important: Browser extensions that intercept clipboard events can block the copy operation.
  • No output generated — Verify the input field is not empty and contains printable characters.
  • Clipboard copy fails — Grant clipboard permissions or copy manually by selecting the text.
  • History not retained — Ensure localStorage is enabled and not cleared by privacy tools.
  • Input file rejected — Confirm size ≤10 MB and that the file is not locked by another process.
  • Dark mode resets — Disable browser settings that force a specific colour scheme or delete conflicting user-style rules.

Advanced Tips

Elevate productivity with the expert practices below.

  • Prefix the encoded string with data:<mime>;base64, to embed images directly in HTML or CSS.
  • Combine URL-safe and No-padding for compact JWT payloads.
  • Chain tr or sed after CLI encodes to perform URL-safe substitutions in scripts.
  • Use the byte counters to estimate bandwidth consumption before deployment.
  • Store frequently used encodings in the history list and pin the page for quick recall.

Glossary

Key terms appear throughout the guide; definitions follow for rapid reference.

Base64
Binary-to-text scheme that encodes three bytes into four printable ASCII characters.
URL-safe Base64
Variant replacing + and / with URL-friendly characters - and _.
Padding
One or two = characters appended to align the final block to 24 bits.
Data URI
Inline resource specification beginning with data: that embeds content directly in HTML.
Expansion Ratio
Proportion by which Base64 increases size; typically 4 / 3 of original bytes.
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