Table of Content

What Are the Best Systems for Usage-Based Billing With Webhook Integrations?

Sep 16, 2026

Team Flexprice

Editorial

Four systems lead here. The best usage billing systems with webhook support are Flexprice, Lago, Orb and Stripe Billing, ranked on the size of the event catalogue, whether the retry schedule is published, and how deliveries get signed. Every billing platform sends webhooks. What separates them is which events exist to send.

Key Takeaways

Webhook depth follows the data model: a platform without a credit wallet or feature entitlements has no wallet or entitlement events to fire, whatever its delivery infrastructure looks like.
Flexprice documents 28 event types across invoices, subscriptions, features, entitlements, wallets, payments and customers, with two delivery modes.
Flexprice's native mode retries 3 times with 1s initial backoff and a 2 minute elapsed cap, while its Svix mode retries at 5 minutes, 30 minutes, 2 hours, 5 hours and 10 hours with dead-letter queues.
Signature verification is the security floor: Flexprice signs with HMAC-SHA256 through Svix, Lago offers JWT or HMAC, and Orb documents alerts rather than a broad event catalogue.

Which usage billing systems have the best webhook support?

Ranked on event catalogue breadth, retry contract, signature verification and sandbox testing.

Flexprice. 28 event types, two delivery modes, published retry schedules.
Lago. Idempotency keys, JWT or HMAC signatures, isolated sandbox orgs.
Orb. Alerting with evaluation SLAs, narrower general event surface.
Stripe Billing. Signed payloads, but no events for primitives it doesn't model.

How do these systems compare on webhooks?

Cells come from each vendor's public documentation as of 19 September 2026.

Capability	Flexprice	Lago	Orb	Stripe Billing
Delivery
Documented event types	28	Documented	Alert-based	Documented
Published retry schedule	Yes, both modes	Yes	Undocumented	Yes
Dead-letter queue	Yes, via Svix	Undocumented	Undocumented	Yes
At-least-once delivery	Yes	Idempotency keys	Undocumented	Yes
Security
Signature verification	HMAC-SHA256	JWT or HMAC	Undocumented	Yes
Secret rotation without loss	Yes	Undocumented	Undocumented	Yes
Event coverage
Invoice lifecycle events	Yes	Yes	Yes	Yes
Wallet and credit events	Yes	Yes	Balance alerts	No
Entitlement events	Yes	Yes	No	No
Parent-child account events	Yes	No	No	No
Testing and hosting
Sandbox environment	Yes	Yes	Test mode	Test mode
Self-host or own VPC	Yes	Yes	No	No

How does each system handle webhooks?

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.

Webhooks run two ways on the same engine. Flexprice Cloud delivers through Svix, and a self-hosted build uses native delivery unless you enable Svix yourself.

The catalogue covers 28 event types: invoice drafted, finalized, paid, voided and overdue; subscription created, updated, paused, cancelled and resumed; plus feature, entitlement, wallet, payment and customer events.
Native delivery retries 3 times with a 1 second initial interval, 10 second maximum interval, 2.0 multiplier and a 2 minute elapsed cap, which suits internal integrations.
Svix delivery gives at-least-once guarantees, dead-letter queues for persistent failures, and a retry schedule of 5 minutes, 30 minutes, 2 hours, 5 hours and 10 hours.
Every Svix request is signed with HMAC-SHA256, and secrets or endpoint URLs rotate without missed events.
Wallet and entitlement events exist because the wallet and entitlement primitives do, so a credit top-up or a feature grant reaches your product without polling. See the webhook documentation for payload formats.

"If billing doesn't work, we don't make money. Flexprice lets us focus on the core business instead of building billing as a second product." - Shubhendu Shishir, Head of Engineering, Simplismart.

Key Takeaways

Webhook depth follows the data model: a platform without a credit wallet or feature entitlements has no wallet or entitlement events to fire, whatever its delivery infrastructure looks like.
Flexprice documents 28 event types across invoices, subscriptions, features, entitlements, wallets, payments and customers, with two delivery modes.
Flexprice's native mode retries 3 times with 1s initial backoff and a 2 minute elapsed cap, while its Svix mode retries at 5 minutes, 30 minutes, 2 hours, 5 hours and 10 hours with dead-letter queues.
Signature verification is the security floor: Flexprice signs with HMAC-SHA256 through Svix, Lago offers JWT or HMAC, and Orb documents alerts rather than a broad event catalogue.

Which usage billing systems have the best webhook support?

Ranked on event catalogue breadth, retry contract, signature verification and sandbox testing.

Flexprice. 28 event types, two delivery modes, published retry schedules.
Lago. Idempotency keys, JWT or HMAC signatures, isolated sandbox orgs.
Orb. Alerting with evaluation SLAs, narrower general event surface.
Stripe Billing. Signed payloads, but no events for primitives it doesn't model.

How do these systems compare on webhooks?

Cells come from each vendor's public documentation as of 19 September 2026.

Capability	Flexprice	Lago	Orb	Stripe Billing
Delivery
Documented event types	28	Documented	Alert-based	Documented
Published retry schedule	Yes, both modes	Yes	Undocumented	Yes
Dead-letter queue	Yes, via Svix	Undocumented	Undocumented	Yes
At-least-once delivery	Yes	Idempotency keys	Undocumented	Yes
Security
Signature verification	HMAC-SHA256	JWT or HMAC	Undocumented	Yes
Secret rotation without loss	Yes	Undocumented	Undocumented	Yes
Event coverage
Invoice lifecycle events	Yes	Yes	Yes	Yes
Wallet and credit events	Yes	Yes	Balance alerts	No
Entitlement events	Yes	Yes	No	No
Parent-child account events	Yes	No	No	No
Testing and hosting
Sandbox environment	Yes	Yes	Test mode	Test mode
Self-host or own VPC	Yes	Yes	No	No

How does each system handle webhooks?

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.

Webhooks run two ways on the same engine. Flexprice Cloud delivers through Svix, and a self-hosted build uses native delivery unless you enable Svix yourself.

The catalogue covers 28 event types: invoice drafted, finalized, paid, voided and overdue; subscription created, updated, paused, cancelled and resumed; plus feature, entitlement, wallet, payment and customer events.
Native delivery retries 3 times with a 1 second initial interval, 10 second maximum interval, 2.0 multiplier and a 2 minute elapsed cap, which suits internal integrations.
Svix delivery gives at-least-once guarantees, dead-letter queues for persistent failures, and a retry schedule of 5 minutes, 30 minutes, 2 hours, 5 hours and 10 hours.
Every Svix request is signed with HMAC-SHA256, and secrets or endpoint URLs rotate without missed events.
Wallet and entitlement events exist because the wallet and entitlement primitives do, so a credit top-up or a feature grant reaches your product without polling. See the webhook documentation for payload formats.

"If billing doesn't work, we don't make money. Flexprice lets us focus on the core business instead of building billing as a second product." - Shubhendu Shishir, Head of Engineering, Simplismart.

AI Billing Is Not Easy, But Flexprice Can Make it Easy

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Lago

Lago publishes webhook delivery with idempotency keys, retries and JWT or HMAC signature verification, and isolates testing in a separate organisation. It's open source under AGPLv3 and its docs benchmark ingestion at 1 to 3M events per second on Kafka, so neither licensing nor throughput separates it from Flexprice. Hierarchy does: Lago's billing entities sit at organisation level rather than modelling parent-child customer accounts, so there is no group-level event to subscribe to and subsidiary roll-ups get assembled in your own code. Flexprice fires them from a native hierarchy.

Orb

Orb's notification surface is built around alerting rather than a broad event bus, with documented evaluation SLAs and alert types covering subscription cost, grouped cost per tenant, rated spend, and credit balance states like depleted, dropped and recovered. The limits are shape and reach: a customer can hold a maximum of one alert of each type per credit balance, and Orb's docs describe no entitlement primitive, so no entitlement events exist to subscribe to. Orb is closed source and hosted. Flexprice ships entitlement and wallet events in the open source tier and runs inside your own VPC.

Stripe Billing

Stripe Billing signs payloads, publishes a full event reference and ships local testing tooling. Coverage is the gap rather than delivery: Stripe Billing models no feature-level entitlements, no recurring or rollover credits and no parent-child accounts, so none of those fire events at all, and teams end up polling their own database for the states that actually gate product access. Flexprice models all three as primitives, so each one has an event to subscribe to.

Frequently asked questions

How should you make billing webhooks idempotent?

Key on the event identifier, not the payload. Store each delivered event ID and drop repeats, because at-least-once delivery means a successful handler can still receive the same event twice after a network timeout. Return 2xx quickly and do the real work asynchronously, since most retry policies treat a slow handler exactly like a failed one.

How do you test webhook integrations before going live?

Run them in a sandbox that mirrors production, then force failures deliberately. Lago isolates testing in a separate organisation, Flexprice supports testing billing changes in sandbox before production, and Svix keeps message history so you can replay a delivery. The tests that matter are the ugly ones: return a 500, time out, and confirm the retry schedule behaves the way the docs claim.