Audit Trail Low-Level Design: Immutable Event Log, Compliance Queries, and Retention
9 min read An audit trail is an append-only log of every action taken on sensitive resources — who changed what, when, and […] Read article
9 min read An audit trail is an append-only log of every action taken on sensitive resources — who changed what, when, and […] Read article
8 min read A subscription pause feature lets users temporarily halt their billing and access without cancelling. Common in SaaS and subscription boxes: Read article
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7 min read Tenant onboarding provisions all the resources a new customer needs to use a multi-tenant SaaS product: creating their account, workspace, Read article
7 min read A notification dispatch system routes outbound notifications — email, SMS, push, in-app — to the right channels based on user Read article
8 min read Real-time document collaboration lets multiple users edit the same document simultaneously, with each user’s changes appearing on others’ screens within Read article
7 min read A payment webhook receiver processes incoming HTTP callbacks from payment processors (Stripe, PayPal, Adyen) notifying your system of payment events: Read article
8 min read Event replay re-processes historical events through a consumer to rebuild state, backfill a new downstream system, fix a processing bug, Read article
7 min read An invitation system lets existing users invite new users via unique links or codes, tracking who invited whom and rewarding Read article
8 min read API key management handles the full lifecycle of programmatic access credentials: creation, scoped authorization, usage tracking, rotation, and revocation. API Read article
7 min read Search suggestion (autocomplete) returns candidate completions for a partial query in under 100ms. The system must handle millions of prefix Read article