Key Takeaways

• Flexprice checks credit balances in real time at under 60ms P99, so a token gate doesn’t add latency to the API call it protects.

• Per-model AI cost tracking shows margin per customer per model, which is the number that decides markup on pass-through inference.

• Credits and Wallets handles prepaid token packs, recurring grants, rollover, stacking order and auto top-ups, from the Scale plan.

• Segwise tracks 100+ enterprise customers on credit billing with zero engineers assigned to credit infrastructure.

• Flexprice bills through Stripe, Razorpay, Moyasar and Nomod on one ledger, which matters for founders selling outside the US.

Which platforms do AI founders use for token and API call billing?

Ranked on what founders raise first: balance checks inside the request, metering per model, prepaid credits, and how long a pricing change takes.

1. Flexprice

2. Metronome

3. Orb

4. Lago

On token and request billing, they compare like this. Read from each vendor’s own docs and pricing on 2026-09-11, with “Undocumented” for anything they don’t publish.

Flexprice

Flexprice is enterprise-grade, open source usage based billing infrastructure for AI and SaaS companies. It can be deployed in your own VPC, on-prem, or on Flexprice’s managed cloud. For an AI product billing on tokens or calls, the constraint is latency inside the request path. Flexprice answers a balance or entitlement check before the call completes, so a credit gate doesn’t turn into a timeout, and it meters several dimensions off one event stream so tokens, requests and model tier all come from a single emission. Cost per model sits next to what you charge, which is what makes markup on pass-through inference a number rather than a guess. What founders use it for:

• Event metering on tokens, requests, minutes or outcomes, at up to 1 million events per second and under 60ms P99.

• Real-time balance and entitlement checks that run before the call completes rather than at invoice time.

• Credit wallets for prepaid token packs, with recurring grants, expiry, rollover and a configurable deduction order.

• AI cost tracking per customer down to the model level, so markup is a measured decision.

• Pricing changes without a deploy, which is what keeps billing aligned with a model release schedule.

• Free to 100K events a month, $500 Build at 1M, $1,000 Scale at 5M, flat and never a cut of revenue.

• “Flexprice processes usage in real-time and credit checks happen in milliseconds without affecting our API performance.”* - Justin Benson, Co-founder

• “Our pricing changes every time we ship a new model, and that’s a lot. Flexprice is the only tool that’s kept up.”* - Navendu A., Head of Business