REST vs GraphQL в iGaming

TL; DR

REST - predictable resources, simple caching/CDN, strong idempotency and webhooks. Excellent for payments, KYC/AML, PSP webhooks, reporting.
GraphQL - flexible selections of "exactly the right fields," aggregation and BFF for client applications. Ideal for game catalog, personalization/recommendations, lobodashboards and camera consoles.
Combo approach: Edge REST for critical domains (payments, compliance) + GraphQL-BFF for UI/widgets and aggregated reads.

1) Domains and typical use cases

2) Performance and traffic

REST: clear resources → easy to cache on CDN by 'GET' + 'ETag/Cache-Control'. The minus is "overfetch/underfetch" for complex UIs.
GraphQL: request exactly the right fields and connections → less traffic on mobile/slow networks; danger N + 1 and "expensive" requests (cost-limits, depth, complexity scoring).

• For UI, GraphQL-BFF over internal REST/gRPC.
• For external integrations and critical operations - pure REST with thin DTO and server expands ('? include = balances, limits').

3) Cache and CDN

REST wins: 'GET' cached on edge; variability via 'Vary '/' ETag'.
GraphQL: client/gateway cache (APQ, persisted queries, response cache per query hash). For public CDN, it is more difficult, but persisted queries with a white list are possible.

4) Version and evolution of contracts

REST: 'v1/v2' in URI/header; add fields - allowed, break - new version. Simple deprecation policy.
GraphQL: non-intrusive changes (adding fields/types) without v2; deletion - via '@ deprecated' and migration windows. More complicated is the discipline of the scheme, you need "schema registry" and linters.

5) Idempotency, retreats, consistency

REST: Natural 'PUT '/' DELETE' idempotency and 'Idempotency-Key' header for 'POST' (payments/refands). Webhooks with 'event _ id' and deadup.
GraphQL: mutations require an explicit idempotence key in input; for criticism - wrap mutations in domain commands on REST/gRPC.

6) Security and limits

• mTLS between gateway and backends, OAuth2/OIDC (JWT, short TTL), ABAC by tenant/roles.

• Thin scopes per route/method, simple rate/quotas.
• Signed webhooks (HMAC + timestamp), allow-list IP.

• Query complexity/depth limit, max nodes/aliases, timeout for resolvers.
• Persisted/whitelisted queries for public clients.
• DataLoader/batching vs. N + 1.
• Field-level authZ policies, PII masking in selectors.

7) Observability and control

Correlation by 'trace _ id '/' span _ id'.
REST: endpoint/method metrics (RPS, p95, 4xx/5xx).
GraphQL: metrics by operation/type, resolver time, "expensive fields," circuit error rate.
Audit: log who and which fields read/mutated (important for KYC/AML/Responsible Gaming).

8) Real time and events

REST webhooks for PSP/game/anti-fraud events (reliability, signature, retrai).
GraphQL Subscriptions - convenient for live widgets (balance, tournament, responsible game limits). Separate channel limits/authorization required.
An alternative is SSE/WebSocket on the REST gateway for simple channels.

9) Multi-tenancy and regions

REST: isolation by routes/domains, per-tenant quotas, simple routing across the region.
GraphQL: one endpoint - strict tenant scoping in context is required, prohibiting cross-tenant fields at the schema/resolver level.
Geo-routing and data-residency: in both approaches - via gateway/policy.

10) Decision Matrix (quick pick)

11) Anti-patterns

GraphQL on top of everything: expensive and unsafe for payment mutations.
REST with ultra-detailed resources: a leapfrog of request chats in UI.

No query limits in GraphQL: DDoS/" expensive query. "

GraphQL without DataLoader: N + 1 avalanche in DB.
Implicit mutation idempotency: doubles in payments/bonuses.
Mixing public and admin APIs in the same graph/domain.

12) Reference pattern for iGaming

Edge REST Gateway (WAF, OAuth2, rate/quotas, webhooks) for payment/compliance domain.
GraphQL-BFF for fronts: aggregates data from internal REST/gRPC, enters field-authZ, complexity-limit, persisted queries.
Service Mesh under the hood: mTLS, traffic policy, circuit-breaker.

13) Version/Contract Issues

REST

Contract = OpenAPI + SDK generation.
Versions: 'v1' → 'v2' with a depression period of 6-12 months.

GraphQL

Contract = SDL + schema registry, breaking change check.
Evolution: '@ deprecated', "sunset" calendar, mailing of diffuse schemes.

14) Implementation checklist

• Defined domains: REST (money/compliance) vs GraphQL (UI/aggregations).
• Gateway: OAuth2/OIDC, mTLS, WAF, rate/quotas.
• REST: 'Idempotency-Key', consistent statuses, webhooks with HMAC.
• GraphQL: persisted queries, complexity/depth, DataLoader, таймауты.
• Auditing/logging of fields, PII masking, tenant-scope.
• Cache: CDN for REST, response cache/APQ for GraphQL.
• Observability: p95 metrics, error budget, "expensive resolvers."
• Deprecation Procedures (REST vN/GraphQL @ deprecated).
• UAT: NFR tests for load, "extensive query" cases, duplicate mutations.

15) Migration Roadmap (if now net REST)

1. Select UI-heavy scenarios (directory, profile, dashboards).
2. Raise GraphQL-BFF over existing REST/gRPC; enable persisted queries.
3. Make field-authZ and difficulty limits.
4. Step by step transfer fronts to GraphQL, leaving the payment loop in REST.
5. Enable shared schema registry and CI breaking-changes checks.
6. Optimize N + 1 (DataLoader), add a resolver level cache.

16) NFT/SLO (landmarks)

REST: incremental latency gateway ≤ 50-80 ms p95, 5xx gateway ≤ 0. 05%, webhooks: delivery p95 ≤ 3 s, duplicates = 0.
GraphQL: p95 request ≤ 300-500 ms for UI; max depth = 8–10; complexity budget per op; Schema error <0. 1%.

Summary

Not "REST or GraphQL," but "both for the intended purpose." Give payments and compliance a stable, predictable REST with strong idempotency and webhooks. Give the interface and analytics a flexible GraphQL-BFF with difficulty limits, field authorization and caches. Connect everything through a single gateway, observability and contract discipline - and get fast UI, reliable money and secure platform evolution.