The BLAST URLAPI is a free public resource provided by NCBI. To ensure the availability of this service and fair access from our users, NCBI imposes a few guidelines for its usage:
a. Limit all scripts to the off peak hours of 9 p.m. to 5 a.m. Eastern Standard Time (USA).
b. For URLAPI scripts, do not send requests faster than once every 3 seconds.
c. While polling for results with RIDs, do not request results at rates greater than once per minute.
d. Please use the '&EMAIL=' field (and the '&TOOL=' for distributed software), in the BLAST URLAPI, so that we can contact you if there is a problem.
e. Plan for errors and unreturned results.
f. Do not write scripts which resubmit failed searches repetitively.
To maintain access to all users, NCBI may cancel long standing searches and block scripts which are flooding the BLAST servers. If you have any questions prior to running scripts please contact [blast-help@ncbi.nlm.nih.gov].