Unicode text
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Round-trips through UTF-8 Base64 without relying on legacy JavaScript string-byte shortcuts.
🔄Base64 Encoder/DecoderReady
Local conversion, not encryption. Text and files are transformed in this browser; this tool does not upload their contents. Base64 makes bytes portable as text, but it does not hide or protect them.
Ctrl/Cmd + Enter to run
Spaces, line breaks, and non-Latin characters are preserved as UTF-8 bytes. Choose a local file when the source is binary.
Capability checkedVerified September 9, 2026
What works
- Encode text through the browser TextEncoder UTF-8 API
- Strictly validate alphabet, length, padding placement, and canonical unused pad bits before decoding
- Keep arbitrary binary bytes intact instead of coercing them into replacement-character text
Important limits
- Base64 is encoding, not encryption or authentication
- A declared media type comes from the supplied data URI or browser file metadata and is not verified from content
What the Base64 Encoder/Decoder does—and does not do
Exact supported inputs, outputs, limits, and primary sources for the current implementation.
Accepted input
- Pasted UTF-8 text up to 10 MiB after encoding, or one locally selected file up to 10 MiB
- Canonical standard Base64 with required final = padding, or canonical Base64URL with either complete padding or no padding
- A data:[mediatype][;base64], URI in Standard Base64 mode
Produced output
- Standard Base64 with required padding, or deliberately unpadded Base64URL
- Decoded UTF-8 text or an exact local binary download when bytes are not valid UTF-8
- A copyable standard Base64 data URI and a preview only for locally chosen or explicitly declared PNG, JPEG, GIF, WebP, or AVIF
Operational limits
- File encoding and decoded Base64 input are capped at 10 MiB
- MIME-wrapped or whitespace-containing Base64, percent-encoded data-URI payloads, Base32, character-set conversion, and streaming conversion are not supported
- Base64URL output omits padding; a data URI is intentionally standard Base64 only
Known limitations
- Base64 is encoding, not encryption or authentication
- A declared media type comes from the supplied data URI or browser file metadata and is not verified from content
- Preview is intentionally restricted to the listed raster formats; all other bytes can still be downloaded
Standards and primary sources
Continue the workflow
Capability claims last reviewed September 9, 2026. Review dates describe the implementation audit, not content freshness by itself.
Use the Base64 Encoder/Decoder with the right expectations
Most Base64 utilities silently accept malformed input, assume every value is text, or label arbitrary bytes as an image. This workbench separates standard Base64 from Base64URL, uses browser UTF-8 APIs for text, checks canonical padding and pad bits, and keeps non-text bytes downloadable. It understands an explicit RFC 2397 data URI but does not invent a media type for bare Base64.
When it is the right tool
- Encoding Unicode text without deprecated escape/unescape workarounds
- Debugging strict standard Base64 versus URL-safe Base64URL
- Encoding a small local file without uploading it
- Inspecting or downloading a binary Base64 payload without corrupting it as text
A deliberate choice
Tooleras keeps this page specific to the job above instead of claiming support for adjacent formats, platforms, or edge cases it cannot verify. Open the capability guide for the exact inputs, outputs, limits, and sources.
Checked examples
Declared data URI
data:image/png;base64,…
Respects the supplied PNG declaration and can preview/download the bytes; bare Base64 gets no guessed image type.
Need a different tool?
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