MCP serverio.github.cyanheads/reference-data-mcp-server

Look up a fundamental physical constant by name, symbol, or common alias. Returns the CODATA 2022 value, SI unit expression, relative standard uncertainty, and a short description.

Look up a periodic table element by name, chemical symbol, or atomic number. Returns the full data record: atomic number, symbol, name, atomic mass (in unified atomic mass units),

Filter periodic table elements by category, group, period, atomic number range, or atomic mass range. At least one filter is required. Returns matching elements as a summary list.

Look up a country by name, ISO alpha-2 code (2 letters), or ISO alpha-3 code (3 letters). Returns the full record: capital, region, official languages, currencies, calling codes, T

Search and filter countries by region, subregion, language, currency, or free-text keyword. At least one filter is required. Returns a ranked list of matching country summaries. Us

Look up an HTTP status code by number or keyword. Returns the reason phrase, description, category (1xx Informational, 2xx Success, 3xx Redirection, 4xx Client Error, 5xx Server Er

Look up a MIME type by type string or file extension. Accepts "image/webp", ".webp", or "webp". Returns the canonical MIME type, known file extensions, whether the type is compress

Convert a local datetime from one timezone to another. Takes a local time string (no UTC offset, e.g., "2026-05-24T15:30:00") interpreted as local time in the source timezone, retu

Get timezone info by IANA ID, country code, or partial city/region name. Returns current UTC offset, standard offset, whether DST is currently active, and major cities in the timez

Convert a numeric value between compatible units of measure. Supports: length (mm, cm, m, km, in, ft, yd, mi), mass (mcg, mg, g, kg, oz, lb, mt = metric tonne / 1000 kg, t = US sho