Cyrillic transliteration to Latin (ISO 9:1995, BGN/PCGN Russian)

Cyrillic transliteration to Latin using a named standard: ISO 9:1995 (one-to-one, with diacritics, covering the full standard: Russian, other Slavic, historic and non-Slavic Cyrillic letters) or BGN/PCGN, which is the Russian system only (Ukrainian, Serbian and other letters are passed through unmapped). Returns the transliteration, the source script, the standard, the mapped fraction and the unmapped characters. Other scripts are rejected with UNSUPPORTED_VALUE.

Output (data): result, source_script (Unicode script name; Latin when the text has no Cyrillic, which is returned unchanged), standard (string: the validated standard, iso-9 by default; on text with no Cyrillic it is echoed although no character needed converting), coverage (0-1 fraction of non-ASCII characters mapped), unmapped (characters passed through). iso-9 maps every letter of ISO 9:1995 (Russian, Ukrainian, Belarusian, Serbian, Macedonian, Bulgarian, historic and non-Slavic Cyrillic, e.g. і -> ì, ѣ -> ě, ә -> a̋, қ -> k̦); a base letter plus combining marks is one unit. bgn-pcgn is the Russian system only: other Cyrillic letters are returned unmapped and lower coverage.

Deterministic: identical input returns identical output, so the response is served with Cache-Control: private, max-age=31536000, immutable (the paying client may cache it indefinitely; shared caches must not, because the response is paid).

Sources: romanisation-tables ISO 9:1995 (full Cyrillic repertoire) and BGN/PCGN Russian system (published 2026-09-29, character correspondences (facts); see sources/translit.md). Echoed in meta.sources.

Price: $0.05 USDC per call (x402, Base). Route contract version 1.0.0. Docs: https://api.duoleads.com/docs#text-transliterate