Search federal grant opportunities using the Grants.gov public REST search API and retrieve opportunity details

Steps

1. No API key is required for the Grants.gov public search API; send a POST request to https://api.grants.gov/v1/api/search2 with a JSON body containing searchParameters such as keyword, oppStatus ('posted', 'forecasted', 'closed'), agencyCode, and CFDANumber.
2. Parse the response opportunityList array; each entry includes oppNumber, title, agencyName, openDate, closeDate, and a synopsis field with funding opportunity description.
3. To retrieve full opportunity details including package attachments and CFDA codes, call GET https://api.grants.gov/v1/api/opportunities/{oppId} using the oppId from the search results.
4. For S2S applicant workflows (automated application submission), a separate PKI certificate-based S2S registration is required; consult the Applicant System-to-System documentation at grants.gov/system-to-system.
5. Use the GetOpportunityList SOAP web service for legacy S2S integrations; the REST search2 endpoint is the current preferred approach for opportunity discovery.
6. Filter results by awardFloor, awardCeiling, and eligibilities fields to pre-qualify opportunities for specific applicant types (nonprofits, state governments, small businesses).