GET /esearch.fcgi

NCBI API key for increased rate limits (10 requests/sec vs 3).

Date field to filter: modification (mdat), publication (pdat), or Entrez (edat).

Constraints: {'enum': ['mdat', 'pdat', 'edat']}

Database to search. Use 'nuccore' for nucleotide database.

Constraints: {'enum': ['nuccore']}

Specific field to search (e.g., 'Accession', 'Organism', 'Title').

Type of identifier to return.

End date for date range filter (format: YYYY/MM/DD, YYYY/MM, or YYYY).

Start date for date range filter (format: YYYY/MM/DD, YYYY/MM, or YYYY).

Return only records modified/created within N days of current date.

Maximum number of UIDs to return (default 20, max 10,000).

Constraints: {'minimum': 1, 'maximum': 10000}

Return format for results.

Constraints: {'enum': ['xml', 'json']}

Index of first UID to return (for pagination).

Constraints: {'minimum': 0}

Type of output. 'uilist' returns list of UIDs, 'count' returns only the count.

Constraints: {'enum': ['uilist', 'count']}

Sort order for results (e.g., 'relevance', 'Accession').

Search term or query using Entrez query syntax. Supports accession numbers, gene names, organism names, etc.

If 'y', store results on server and return WebEnv and query_key for subsequent calls.

Constraints: {'enum': ['y']}