NCBI Entrez E-utilities API
Science & Math · Operational · 30d uptime 100%
Search and retrieve biomedical literature, genes, proteins, nucleotide sequences, structures, taxonomy, and other Entrez databases.
Trust signals
Pricing
FREE
Auth
NONE
CORS
Yes
Rate limit
3 requests/second without API key; 10 requests/second with API key
Health
182ms
Trust score
94 (A)
Last checked Oct 19, 2026 · uptime 24h 100% / 7d 100% / 30d 100%
Excellent production-readiness signals.
Links
- Homepagewww.ncbi.nlm.nih.gov
- Documentationwww.ncbi.nlm.nih.gov/books/NBK25501/
- Base URLwww.ncbi.nlm.nih.gov/books/NBK25501/
Integration checklist
- Auth is NONE— no credit card required
- CORS enabled — callable directly from browsers.
- Rate limit: 3 requests/second without API key; 10 requests/second with API key