Unicode Escape / Unescape

How each character is written

Encode walks the text one character at a time. For a character in the range that fits in sixteen bits, it prints a backslash, a u, and exactly four hex digits, using zeros on the left when the number is small. Letters stay in that form too, so H is not left as H. The space between Hello and the check mark is \u0020, not a typed space. The check mark is \u2713. The whole sample is one continuous string with no separators.

A character above that sixteen-bit range is split into the two surrogate numbers and each is written as its own four-digit escape. The emoji 😀 encodes as 😀. Decode of that pair puts the two units back next to each other, so the emoji returns. A brace form is accepted only on decode: \u{1F600} is also the emoji, in one replacement, because the braces hold the full number. Encode never writes the brace form. It writes the pair.

Decode scans for either the brace form or a backslash, a u, and exactly four hex digits. The digits may be either case. Text that does not match is copied through. Hello \u0021 becomes Hello !. A short fragment such as \u12 has only two digits, so it is left unchanged. The page does not turn \n, \t, or \x41 into anything. Those sequences are ordinary characters here unless they happen to contain a four-digit \u form.

Encode, Decode, and Run

The direction buttons are a pair. The pressed one is the direction Run will use. Changing it updates the label and the placeholder and does not touch Output. You can prepare a new paste and press Run once. The status line starts as Switch between plain text and Unicode escape sequences. After a successful encode it reads Unicode escapes generated. After a successful decode it reads Unicode escapes decoded.

Copy output copies Output after Run. If you switch direction and forget to run, the clipboard still has the previous direction's result. There is no download. The page does not store the box. A reload returns to Encode and an empty box.

When an escape sequence is the right form

Use this page when a source file wants \u escapes, or when you have those escapes and want the characters. JSON and JavaScript strings that also escape quotes and newlines belong on string escape, which has a syntax menu this page does not. A JSON string that is itself wrapped in quotes belongs on JSON unescape. HTML entities such as named ampersands belong on HTML encode / decode. Percent-encoding for a URL belongs on URL encode / decode. None of those write this four-digit form for every character.

This page escapes the whole box, including letters and spaces. It is not a tool that escapes only the characters outside ASCII and leaves Hello as Hello. If you need the readable letters to stay, this encoder is the wrong pass.

Short escapes, braces, and characters the encoder splits

Four digits are required for the bare form. Three digits, or a \u with no digits, stay as typed on decode. The brace form allows a longer number and is how a single escape can name the emoji without a surrogate pair. Encode will not produce that brace form even if you decoded one a moment ago. Run in Encode always uses the pair for those characters.

Lowercase digits are what encode writes. Decode accepts uppercase and returns the same character. A mixed string such as ABC\u0021 keeps ABC and replaces only the escape. There is no option to escape as \U, as a brace, or as a HTML numeric entity. Those are different spellings. The failure message is generic. It does not name the bad index.

Rules and limitations

Encode writes \u and four lowercase hex digits per sixteen-bit unit. Characters that need a surrogate pair become two escapes. Spaces are escaped. The brace form is not used on encode.

Decode replaces \u{hex} and \u plus exactly four hex digits, and copies every other character through. Direction changes do not run. Copy output follows the last Run. There is no download and no saved text.

Common problems

If the space in Hello ✓ became a visible gap in your editor, you are looking at the Decode placeholder. The encoded space is \u0020.

If an emoji came back as two escapes, that is the encoder's pair. Decode accepts that pair and also the brace form. Encode will write the pair again.

Frequently asked questions

About this tool

Maintained by Toolbench. For large or deeply nested files, split the input into smaller batches and verify representative results before using them in an import or application. Report reproducible problems through Contact.