LAURI PESONEN

Collaborative visual workspace — boards, docs, and project management. Full-stack work across a Clojure/PostgreSQL backend on AWS and a ClojureScript/React frontend, in a small team where engineers and designers owned projects directly.

• Tasks & Projects Lead backend engineer on the project-management expansion, a Linear-style surface built to turn Whimsical from an occasional diagramming tool into part of users’ daily work. Designed the project data model — configurable statuses, custom fields, and a task filter language — and extended the backend with My Tasks and a file-attachment API.
• Entitlements & monetisation Built the feature-gating system that controls which capabilities each plan tier unlocks, from Free through Enterprise — the enforcement layer tying product features directly to revenue. Built the credit-based metering for the AI features, and added prompt caching after noticing Whimsical’s own demo prompts would exhaust a free user’s monthly credits on first use.
• Platform modernisation Instigated and drove the conversion of the backend web layer from asynchronous to synchronous — faster compiles, readable stack traces, fewer concurrency mistakes. A strangler-fig approach kept the migration transparent to ongoing delivery. The migrated surface handles several hundred thousand requests/week in production, with the busiest endpoint at p50 16ms / p95 70ms.
• Reliability infrastructure Built, on my own initiative, a watchdog service that pages the team when a recurring background job silently stalls, and a queue-based migration framework on which I ran tens of production data migrations.

Fintech challenger bank. Worked on personal loans and payments. Identified that the core monetary transaction flow, spanning multiple microservices, was too fragile to extend safely with new products, and redesigned it to be fault-tolerant with a clean API for new client services.

Full-stack web contracting across a wide range of technologies, typically hired for breadth and to coach junior engineers. Projects included an IoT connectivity service (Go, RabbitMQ, React), a GIS data service (Node, PostgreSQL), and an OAuth2 client management service (Go, Ember).

Tech lead on a Clojure/Datomic event data (e.g. theatre show times) API. Built the Elasticsearch search, Redis-based rate limiting, and JWT authentication. Owned the team backlog, drove design consensus, and reviewed code.

Built multiple C# database-tooling products — SQL Scripts Manager, SQL Virtual Restore, SQL HyperBac, SQL Storage Compress. Implemented Azure web services for analytics event processing. Member of the engineering steering group; ran the internal Clojure user group.

Core engineer on the Apama Complex Event Processing platform. Implemented green-thread scheduling with continuations to replace a native-thread model, and built a hierarchical logging system.

Designed and implemented a proprietary network element for a mobile operator with five-nines availability and soft real-time requirements. Implemented a Ruby DSL for generating C event-type structures. Administered a 20-server Solaris development environment.