Apply for WEX fleet card API access through the WEX developer partner program and obtain your API credentials and sandbox environment details.
Authenticate requests using the OAuth 2.0 client credentials flow to obtain an access token; include it as a Bearer token on all API calls.
Call the accounts endpoint to retrieve fleet account details including card list, spending limits, and vehicle assignments for the fleet.
To authorise a fuel or service transaction, POST a pre-authorisation request with the card number (tokenised), merchant category, and requested amount; capture the auth code from the response.
Complete the transaction by POSTing the settlement request with the auth code, actual transaction amount, and odometer reading (required for fleet cards).
Retrieve transaction history via the transactions endpoint with date range filters for fleet fuel cost reporting and per-vehicle expense allocation.
Known gotchas
WEX fleet cards require odometer entry at the pump for many product codes; if odometer data is unavailable from telematics, the transaction may be declined — implement a fallback prompt.
WEX sandbox credentials and live credentials use different base URLs; ensure environment configuration switches correctly before going to production.
The WEX API is partner-gated; endpoint paths and schemas provided in this route are illustrative — refer to the official WEX developer documentation obtained at onboarding for canonical details.
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