{"product_id":"ai-client-spend-caps-with-webhooks-openai-data-tables","title":"AI Client Spend Caps with Webhooks, OpenAI \u0026 Data Tables","description":"\u003ch3\u003ePut a hard cap on AI spend per client—automatic enforcement with webhooks + Data Tables + OpenAI-compatible limits\u003c\/h3\u003e\n\u003cp\u003eThis n8n workflow enforces \u003cstrong\u003eAI Client Spend Caps\u003c\/strong\u003e for multiple clients. Every request is checked against a Data Table usage ledger, and once a client hits (or exceeds) their cap, the workflow immediately returns \u003cstrong\u003eHTTP 429\u003c\/strong\u003e—without calling your OpenAI-compatible model.\u003c\/p\u003e\n\n\u003ch3\u003eWhat this workflow does\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eReceives client requests via webhook:\u003c\/strong\u003e A \u003ccode\u003ePOST\u003c\/code\u003e request includes \u003ccode\u003eclient_id\u003c\/code\u003e and \u003ccode\u003eprompt\u003c\/code\u003e, secured with \u003cstrong\u003eheader authentication\u003c\/strong\u003e.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eResolves usage period + cap:\u003c\/strong\u003e The workflow validates the request, determines the current usage window (\u003cem\u003emonth\/day\/all-time\u003c\/em\u003e), and calculates the cap using a \u003cstrong\u003edefault value\u003c\/strong\u003e plus optional \u003cstrong\u003eper-client overrides\u003c\/strong\u003e.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eReads usage from an n8n Data Table:\u003c\/strong\u003e It looks up the current period record using a \u003ccode\u003erow_key\u003c\/code\u003e formatted as \u003ccode\u003eclient_id|period\u003c\/code\u003e.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eHard-stops at the limit:\u003c\/strong\u003e If the client’s spent amount is at or over the cap, the workflow returns \u003cstrong\u003eHTTP 429\u003c\/strong\u003e immediately.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eCalls OpenAI-compatible chat completions only when allowed:\u003c\/strong\u003e If under the cap, it sends the prompt to the configured \u003ccode\u003echat\/completions\u003c\/code\u003e endpoint.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eRecords usage + returns results:\u003c\/strong\u003e It extracts token usage from the provider response (or estimates it), updates \u003ccode\u003espent\u003c\/code\u003e and \u003ccode\u003ecalls\u003c\/code\u003e in the Data Table, and returns the answer plus updated usage details.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eUse cases\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003eAgencies running AI workflows for multiple customers and needing predictable \u003cstrong\u003eusage-based billing controls\u003c\/strong\u003e.\u003c\/li\u003e\n  \u003cli\u003eFreelancers deploying a shared AI endpoint where each client must have a strict \u003cstrong\u003espend limit\u003c\/strong\u003e.\u003c\/li\u003e\n  \u003cli\u003eSaaS operators building internal tooling to prevent unexpected model costs per customer and per period.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eTechnical details\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eWebhook\u003c\/strong\u003e with \u003cstrong\u003eHeader Auth\u003c\/strong\u003e for incoming requests.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003en8n Data Table\u003c\/strong\u003e named \u003ccode\u003eclient_spend\u003c\/code\u003e with columns: \u003ccode\u003erow_key\u003c\/code\u003e, \u003ccode\u003eclient_id\u003c\/code\u003e, \u003ccode\u003eperiod\u003c\/code\u003e, \u003ccode\u003elast_call_at\u003c\/code\u003e, \u003ccode\u003espent\u003c\/code\u003e, \u003ccode\u003ecalls\u003c\/code\u003e.\u003c\/li\u003e\n  \u003cli\u003eNodes\/logic: \u003cstrong\u003eif\u003c\/strong\u003e, \u003cstrong\u003eset\u003c\/strong\u003e, \u003cstrong\u003ecode\u003c\/strong\u003e, \u003cstrong\u003ewebhook\u003c\/strong\u003e, \u003cstrong\u003edata table\u003c\/strong\u003e (plus sticky note for documentation).\u003c\/li\u003e\n  \u003cli\u003eOpenAI-compatible model call to \u003cstrong\u003e\u003ccode\u003echat\/completions\u003c\/code\u003e\u003c\/strong\u003e and automatic \u003cstrong\u003eHTTP 429\u003c\/strong\u003e rejection when capped.\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"N8N Commerce","offers":[{"title":"Default Title","offer_id":46154012623027,"sku":"N8N-20290","price":23.99,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0749\/6279\/6723\/files\/lID57_oKzQsQVCrZIpCXm_GYSixtKD.png?v=1790932645","url":"https:\/\/buyflowscripts.com\/products\/ai-client-spend-caps-with-webhooks-openai-data-tables","provider":"N8N Commerce","version":"1.0","type":"link"}