Best usage-based billing software for API teams

On Stripe with simple pricing, start with Stripe Billing's meters; Metronome (which Stripe owns and now recommends for new integrations), Orb, Chargebee and Lago handle pricing that outgrows them. Pick Polar if you want someone else to handle sales tax, and Zuplo if you're happy to route traffic through a gateway that also does keys, rate limits and billing. The billing engines don't issue API keys or rate-limit requests, so if you need those without a gateway, look at Kinde (keys and billing, no rate limits) or UsageRail (all three, though its Stripe billing isn't live yet; we build it).

The tools at a glance

What each tool covers

"No" means we didn't find the feature on the vendor's pricing page or in its docs.

What one API would pay each tool

Take one API: $5,000 a month billed to 150 customers, 10 million requests, one usage event per request. Here is each tool's own fee at list price, cheapest first.

The rows don't cover the same work, so read them with the coverage table. Card fees, about $190 here at Stripe's US rate, come on top of every row. Stripe's 0.7% Billing fee ($35 here) applies wherever subscriptions live in Stripe Billing: Autumn says so on its pricing page, and UsageRail also keeps subscriptions in your Stripe Billing. Event fees drop if you send per-minute totals instead of one event per request.

Polar is left out because it charges no separate card fee on top of its own. On its Pro plan this API would pay about $270 all in, versus about $190 of card fees elsewhere, and Polar takes on the sales tax. Our Stripe fee calculator works out card fees for your own mix.

Billing engines: you send usage, they invoice

These six price the usage your code sends and produce invoices. Keys, rate limits and cutting off a customer stay in your code (or, for OpenMeter, in Kong's gateway).

Stripe Billing

It's the natural start if your card payments already run through Stripe. You send usage to the Meters API, put a metered price on the subscription, and Stripe adds the usage to each invoice. Stripe's docs now call Metronome the recommended starting point for new usage-based integrations, but these basic meters remain fully supported, and Stripe's own comparison gives them full Checkout support where Metronome's is limited.

Stripe charges 0.7% of billing volume and includes up to 100 million meter events a month.

Everything in front of the invoice is yours to build. Stripe doesn't issue API keys to your customers or limit their requests; Entitlements tell you when to grant or revoke a feature. Credits are only reconciled at invoice time, so a customer can run past their balance mid-month. The portal can cancel a usage-based subscription but not change it, and the embeddable pricing table doesn't support usage-based prices. Our Stripe usage-based billing walkthrough has the setup in code.

Metronome

Metronome is now part of Stripe and is built for heavy event volumes: billable metrics can be SQL over raw events, rate cards handle commits and credits, and alerts fire on usage and balances. Invoices are created in your Stripe account, and embeddable dashboards show customers their invoices, usage and credits.

The self-serve Startup plan charges 0.8% of billing volume plus $0.04 per 1,000 ingested events; Custom plans go through sales.

Model the event fee first: 10 million raw events a month adds $400, so pre-aggregate. There are no API keys or rate limits, and Metronome alerts you rather than stopping requests. Stripe's comparison also rates Checkout support with Metronome as limited, needing custom API calls and webhooks, so expect to build more of the sign-up flow.

Orb

Orb is a usage billing engine that Adyen finished acquiring on July 1, 2026; its docs still list Stripe alongside Adyen as a payment gateway. Its strengths are pricing detail and credits: a prepaid credit ledger, balance alerts and webhooks, and a hosted invoice portal where customers see invoices, current usage and the upcoming bill, and pay.

Credits cost $6 each, less with volume discounts. One credit covers $1,000 of billings or 200,000 ingested events (Orb's figure: 0.60% of billing volume plus ingestion), and new accounts get 100 free.

Orb doesn't block anything itself. Its guide to gating access on prepaid credits has your code check a flag on every request, updated from webhooks and the balance API, and warns that a customer may get a few requests through after running out. Its docs don't cover checkout, API keys or rate limits.

Chargebee

Chargebee is subscription billing software that has added usage billing. It takes raw or pre-aggregated usage over its API and comes with hosted checkout, a customer portal, pricing tables and more than 40 payment gateways. With Stripe as the gateway, Stripe processes each charge and Chargebee runs subscriptions, invoicing, dunning and reconciliation.

The self-serve Flow plan costs $0 a month plus 0.80% of monthly invoicing volume, or $99 plus 0.65% (cheaper above $66K a month), with 100 million usage events included.

For a small API team it's a heavier move. Chargebee replaces Stripe Billing as the record of your subscriptions, its other products (quoting, revenue recognition) target sales and finance teams, and prepaid credits are still in early access. No API keys or rate limits.

Lago

Lago is open-source billing (AGPL-3.0) you can self-host or use as Lago Cloud. It ingests usage events, runs plans and invoices, and keeps wallets for prepaid credits with top-ups, priorities and expiry dates. Its customer portal shows invoices, usage and credit balance, takes top-ups, and embeds in your app with an iframe. With Stripe connected, Lago issues the invoice and Stripe collects payment.

Self-hosting is free; Lago Cloud and Premium have no public prices.

What's missing for an API seller: a checkout where a new customer picks a plan and pays (Lago's Stripe link only saves a card), and a real-time wallet balance outside Premium. No keys or rate limits.

OpenMeter (Kong Konnect Metering & Billing)

OpenMeter is now part of Kong, and its hosted version is now Konnect Metering & Billing; the open-source project (Apache-2.0) can still be self-hosted. You send usage to its API as CloudEvents, and it handles entitlements, usage limits, credits and subscriptions, using Stripe to send invoices, calculate tax and collect payment.

On Kong's Plus plan it costs from $25 a month, plus $20 per million events (up to 10 million) and 0.4% of billing volume (up to $250,000), with a 30-day free trial.

Enforcement is the catch. Kong's docs describe blocking requests at the gateway when a customer hits a limit, and keys and rate limiting are Kong Gateway plugins. Without the gateway, stopping a customer is your code's job.

Pricing layers on top of your Stripe

Autumn and Schematic hold plans, limits and credit balances, answer whether a customer may do something, and keep Stripe in step; Stripe still sends the invoices.

Autumn

Autumn connects to your existing Stripe account and handles plans, usage limits and credits. You call check before an action and track after it; top-ups, auto top-ups, rollovers and spend limits are built in. New customers pay through Stripe Checkout, Stripe's billing portal covers payment methods, invoices and cancellation, and the API returns usage for your own billing page. The code is open source (Apache-2.0).

The free plan covers 8K of monthly billing volume (the page gives no unit) and 10 million Autumn API calls. Pro is $375 a month for up to 50K and 20 million calls, then $5 per million.

Each check and track is a network call to Autumn; an edge cache that answers from your own AWS account is in private preview. There are no API keys, and spend limits cap money, not requests per second.

Schematic

Schematic's SDKs fetch a customer's entitlements once, then check them locally with updates pushed over a WebSocket; a self-hosted Replicator removes the outside call entirely. It has credits (bundles, auto top-up, reservations for parallel work), checkout, and an embeddable customer portal where customers change plans, see invoices and usage, and buy credits. Stripe or Metronome issues the invoices, synced both ways.

Starter is free up to $5K billed a month with two custom plans; Growth is $400 a month for 15 plans and 20 overrides; Enterprise is quoted.

There are no API keys (Schematic's "keys" identify companies and users) and no request rate limits: its usage controls cap the credits a customer can spend per hour, day or request.

Tools that do more than billing

Each of these also takes on a second job: sales tax, the gateway, login, or keys and limits.

Polar

Polar is a merchant of record: it resells your product, so it takes on international sales tax, registers in other countries and files for you. It has an events API, meters, metered prices, meter credits, checkout, and a hosted portal where buyers manage subscriptions, invoices, payment methods and license keys (plan switching and usage views are optional). License keys can carry a usage quota that counts up with each validation.

Starter takes 5% + 50¢ per transaction with no monthly fee. Paid plans lower the rate, from Pro ($20 a month, 3.8% + 40¢) to Scale ($400, 3.4% + 30¢). Non-US cards add 1.5%, disputes cost $15, and payouts carry Stripe's payout fees.

Your money arrives as payouts, not in your own Stripe account, and the portal looks the same for every Polar seller. License keys are validated through Polar's API (it suggests once per session), and there's no rate limiting.

Zuplo

Zuplo is an API gateway with billing built in: keys, per-key rate limits, quotas, plans and invoices in one product. Customers subscribe through Stripe Checkout in its developer portal, which also has the pricing page, usage dashboards and key management. A customer who hits a hard quota gets a 403 immediately, and Zuplo issues a Stripe invoice at period end. Monetization launched as a public beta in March 2026, and going live still means emailing Zuplo's sales team.

Free covers 100K requests a month, then rate-limits until the next cycle. Builder is $25 a month for 100K requests plus $100 per extra 100K, capped at 1M a month, 1,000 keys and two developer seats ("not a team plan", in Zuplo's words). Both include 100K monetization events. Enterprise starts at $1,000 a month, billed annually, with monetization as an add-on.

The trade-off is the gateway: every request runs through Zuplo, which also holds your plans and usage instead of Stripe Billing. Prepaid credits are marked "Coming Soon".

Kinde

Kinde is a login product that has added billing and API keys. Your customers get API keys (with a self-serve key screen on Plus), plans come with a pricing table for sign-up and the self-serve portal, usage is recorded through its Management API, and credit packs sell as one-time purchases.

Pro is $25 a month plus a 0.7% billing fee, Plus $75 plus 0.6%, Scale $250 plus 0.5%. API keys include 1.5 million verifications, then $0.0001 each.

Kinde creates a new Stripe account for you rather than using your existing one, which it says Stripe requires for third-party integrations. Every key check calls Kinde's verify endpoint; its sample code caches valid results for five minutes, so with that cache a revoked key keeps working until the entry expires. Rate limits and stopping a customer at a limit are up to you.

UsageRail

UsageRail is our product, so weigh this entry accordingly. It's an open-source SDK (MIT) plus a hosted service: the SDK checks API keys, applies per-customer rate limits and enforces quotas inside your own process, so requests never pass through us. Plans, checkout and invoices run on your own Stripe account, quotas can bill overage, stop at the limit or draw down prepaid credits, and customers get a hosted portal for keys, usage, plan changes and credits.

It's free until you bill $1,000 a month through it, then $29, $79 or $199 a month, with no revenue share (full pricing).

The gaps: it's new, and billing through Stripe (plans, checkout, usage invoices) isn't live yet; keys, limits, quotas and the portal are. It has no gateway features such as caching or a firewall, and it doesn't handle sales tax. SDKs are Node.js and Python at launch; other languages use an HTTP check that adds a network call per request. Rate limits count per server instance by default, Stripe sees usage only after each period ends, and open-source pieces on free tiers cost less if you wire them together.

Other tools on these lists

Also common in other roundups:

• Stigg, a usage runtime for credits, entitlements and metering that works with your existing billing provider, overlaps with Schematic and Autumn. Build is free for 10,000 managed entities and 5M usage events a month, with Stigg branding on widgets; Pro is $499 a month ($399 billed annually).
• Flexprice is open source (AGPL-3.0); its cloud plan is $199 a month plus 0.5% of billing, with up to 50M usage events. It's closest to Lago.
• m3ter, now part of Salesforce, doesn't publish prices and says it's priced for mid-size and large B2B SaaS companies.
• Unkey isn't billing software: it issues API keys, rate-limits them and caps per-key usage, with a hosted key portal in beta. Its docs have you build invoices from its usage data, and each key check is an HTTP call to Unkey. Free covers 150K valid requests a month; paid tiers start at $25.
• RapidAPI is a marketplace: since November 15, 2025 it takes 25% of payments through its API Hub, processing included, and pays out only via PayPal.

How we compared

We looked at what a team selling an API needs: how usage is counted, checkout, invoicing, prepaid credits, API keys, rate limits, a customer portal, whether traffic must pass through the vendor, and how each tool charges. If you're still deciding what to meter, start with our guide to usage-based billing for APIs.

Every price and feature comes from the vendor's own pricing page or docs, read on October 20, 2026; where a vendor doesn't publish a price, we say so. We compared documentation rather than running traffic through each tool, so confirm the limits that matter to you. Prices checked October 2026; we re-check monthly.

We build UsageRail, so we aren't neutral. Its entry lists its gaps. It opened in October 2026 and its Stripe billing isn't live yet, so the billing parts describe the design: published prices, no measured results yet.

How to choose

You only need invoicing on Stripe

Use Stripe Billing and write the key checks and limits yourself. It adds one 0.7% fee and no new system.

You need a merchant of record

Use Polar. You pay a bigger cut per payment and get payouts instead of money in your own Stripe account, but you never register for or file sales tax.

You already run a gateway

Bill where the traffic is: Zuplo if you're on it or willing to move, Konnect Metering & Billing if you run Kong.

Your pricing has commits, contracts or many meters

Compare Metronome and Orb on your real event volume, since both charge per ingested event. Chargebee fits if your subscriptions already live there.

You want to host billing yourself

Lago and OpenMeter are open source. Lago includes a customer portal; OpenMeter pairs with Kong.

You want plans and credits on Stripe

If you'll handle API keys yourself, Autumn and Schematic both have free tiers. Schematic checks entitlements locally; Autumn calls its API on every check.

You need keys, limits and billing without a gateway

Kinde covers keys and billing if you also want its login and can start on a new Stripe account, but you'd add rate limits yourself. UsageRail is built for this case, on your existing Stripe account, once its Stripe billing is live.