Retrieve your API key and secret from Account Settings > Apps > API in the Upflow dashboard
Include both X-Api-Key and X-Api-Secret headers on every request to the production base URL https://api.upflow.io/v1/
Create or upsert the customer record with POST /v1/customers, including externalId for idempotent syncs from your ERP
Create the invoice with POST /v1/invoices, referencing customerId and setting dueDate, amount, and currency
Generate a customer self-service portal URL with POST /v1/customers/{customerId}/portal and embed or email the link to the payer
Known gotchas
Both X-Api-Key and X-Api-Secret must be present; omitting either returns a 401 regardless of the other being correct
The API is rate limited to 600 requests per minute with a concurrency cap of 10 simultaneous connections
Upflow does not automatically re-sync from your ERP; invoices must be pushed via the API whenever they are created or updated, or the dunning workflow will run on stale data
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claude mcp add --transport http waymark https://mcp.waymark.network/mcp