Which input formats are accepted?

You can mix U+1F30D, 0x41, backslash-u escapes and bare decimal numbers in one list, separated by spaces or commas. Tokens that contain hex letters or a hex prefix are read as hexadecimal; all-digit tokens are read as decimal.

How is a code point turned into characters?

Each numeric code point is passed to the standard String.fromCodePoint, which produces the correct UTF-8-representable character, including emoji and other characters above U+FFFF that need surrogate pairs internally.

Why are some values rejected?

Values above U+10FFFF are outside the Unicode range, and values in U+D800 to U+DFFF are surrogate halves that are not valid standalone characters. Both are flagged as errors rather than producing broken output.

Can I paste a bare hex list without prefixes?

Yes if the values contain hex letters they are detected as hex automatically. Ambiguous all-digit tokens are treated as decimal, so prefix them with 0x or U+ if you mean hex.

Is this the reverse of the code-point exploder?

Exactly. The UTF-8-to-code-points tool decomposes text into numbers; this tool recomposes those numbers back into text, making the two a matched encode/decode pair.

Unicode Code Points to UTF-8

From code points back to text

This tool is the inverse of a code-point exploder: give it the numeric Unicode code points and it reassembles the original characters. It is handy when a log, API response or escape sequence gives you raw code-point numbers and you want to see what they actually spell.

How it works

The input is split on spaces and commas into tokens, and each token is classified:

U+, 0x, \u, \U prefix      -> hexadecimal
contains a-f letters       -> hexadecimal
all decimal digits         -> decimal

The token is parsed to an integer in the right base, validated against the Unicode range (U+0000 to U+10FFFF) and against the surrogate gap (U+D800 to U+DFFF, which are not real characters), then passed to String.fromCodePoint. That builtin correctly emits a single character even for astral code points that JavaScript must store internally as a UTF-16 surrogate pair.

Tips and notes

You can mix notations in a single list — U+0047 0x65 114 61 is perfectly valid and resolves to “Gera” minus the last letter, for instance. If you have an ambiguous all-digit value that is meant to be hex, add a 0x or U+ prefix so it is not misread as decimal. Surrogate or over-range values are rejected with a clear message rather than silently producing the replacement character.