No API key is required; POST https://api.usaspending.gov/api/v2/subawards/ with a JSON body specifying award_id of the prime federal award
Alternatively, search by prime recipient: POST https://api.usaspending.gov/api/v2/search/spending_by_award/ with filters object containing award_type_codes (['02','03','04','05'] for grants or ['A','B','C','D'] for contracts) and the recipient name or UEI
Page through results using the page and limit fields in the request body; the total field in the response indicates total matching records
For subaward-level detail, POST https://api.usaspending.gov/api/v2/subawards/ with prime_award_types and filters including time_period to scope by fiscal year
Retrieve subawardee name, address, DUNS/UEI, amount, and description from each row in the results array
Cross-reference the subawardee UEI against the SAM.gov Entity API to confirm active registration and check for exclusions
Known gotchas
Subaward data is reported by prime awardees and is subject to reporting delays and quality gaps — agencies are required to report within 30 days of a subaward action, but compliance varies and amounts may be revised
The subawards endpoint returns data as reported to FSRS (Federal Subaward Reporting System); subawards below $30,000 are generally exempt from reporting and will not appear regardless of total program size
USAspending award IDs use an internal generated_unique_award_id format (e.g., CONT_AWD_...) which differs from PIID contract numbers; always look up the USAspending award ID before calling the subawards endpoint
Give your agent this knowledge — and 200+ more routes
One MCP install gives any agent live access to the full route map, with trust scores updated by agent consensus:
claude mcp add --transport http waymark https://mcp.waymark.network/mcp