Track rising LLM API spend and cut costs with per-call attribution

Executive Summary

Many engineering, SRE and finance teams at software-using companies are losing visibility into rapidly rising LLM API spend because tokenized, per-call billing is highly granular, scattered across providers, and rarely mapped back to code, feature or customer-level metrics. This lack of attribution becomes acute for teams running multiple models in production where dozens of small calls compound into unpredictable monthly bills. You could build a developer-first observability product that instruments LLM calls and attributes each token and API call to the originating service, feature flag, commit or customer, then normalizes costs across providers and surfaces cost per feature, team and customer. Key components would be lightweight SDKs for major languages, automatic correlation with tracing/CI systems, connectors to billing APIs, and actionable controls such as budget alerts, throttles and suggested prompt rewrites. The go-to-market assumption of roughly $3K ACV per company maps to a TAM of $18.0B (6M software-using companies x $3K), and the market scoring (90/100) and revenue potential (88/100) indicate strong commercial opportunity if adoption hurdles can be managed. This moment is favorable because LLM adoption is accelerating, tokenized billing is making costs more granular and harder to forecast, and modern DevOps teams expect the same traceability for compute costs that they get for performance and errors. To stand out you must deliver highly accurate, low-overhead attribution across vendors and ship polished integrations with OpenAI, Anthropic, major cloud providers and common observability stacks, while addressing privacy and security concerns around payloads. The main challenges are instrumenting legacy paths, normalizing disparate billing models, and winning developer trust, but the strengths are a clear ROI story, limited direct competition focused on per-call attribution, and a path to expand into automated cost optimization and reclamation.