QuotaStack Concepts
Everything you need to understand how QuotaStack works. Start with the system overview, then dive into any concept.
How QuotaStack works
Your app funds customer accounts via topups or subscriptions, checks entitlements before actions, meters usage to debit credits, and reserves credits for long-running operations — all on an append-only ledger with idempotency guarantees and webhook notifications.
How It Fits Together
Fund
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Store
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Use
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Infra
All Concepts
Read in order for a complete understanding, or jump to any concept.
1
Credits
How QuotaStack stores, grants, debits, and tracks credits using millicredits, credit blocks, and an append-only ledger.
2
Entitlements
How to check whether a customer can perform an action, how entitlement results are computed, and how caching keeps checks fast on the hot path.
3
Metering
How to define billable metrics, configure metering rules with flat/per-unit/tiered pricing, and record usage events that debit credits.
4
Reservations
How to hold credits during long-running operations using the reserve/commit/release lifecycle, with TTL-based auto-expiry and concurrency safety.
5
Topups and Wallets
How to grant credits after payment, model wallets and credit packs, configure topup packages, and control burn order with priority.
6
Subscriptions
Optional recurring billing state management with prepaid and postpaid modes, credit grants on renewal, rollover, and contract lifecycle.
7
Idempotency
How QuotaStack prevents duplicate operations using the Idempotency-Key header, server-side locks, and deterministic key conventions.
8
Webhooks
Event delivery from QuotaStack to your application, with HMAC-SHA256 signing, retry schedule, and event catalog.
9
Customer Identification
Two identifier types and two URL forms for customers — when to use each, and how to avoid mixing them.
10
API Conventions
Environments, authentication, rate limits, pagination, error format, and retention — the cross-cutting details every integration needs.