Karl-aksel Puulmann
Senior Software Engineer at Plausible Analytics
Tartu, Tartu maakond, Estonia
Summary
🤩
Rockstar🎓
Top SchoolKarl-aksel Puulmann is a senior software engineer with 14 years of experience building high-performance analytics, data ingestion, and product features for scale. He’s an early PostHog contributor who implemented session recording, optimized ClickHouse queries over billions of datapoints, and built benchmarking and observability tooling to keep large data pipelines healthy. At Plausible he focused on backend performance and query optimizations for a privacy-first analytics stack, and his open-source work spans both frontend type safety (mapbox-gl typings) and backend database tooling (pgcli, ClickHouse). A former CTO who led large product initiatives—including an offline-first mobile app and maps engine for farmers—he combines hands-on engineering with systems-level thinking and practical operational experience. Colocated in Tartu, Estonia, he brings a rare mix of data engineering, performance tuning, and product-driven code craftsmanship.
14 years of coding experience
9 years of employment as a software developer
Nõo ReaalgümnaasiumBSc Computer Science, BSc Computer Science at University of Tartu
Estonian, English
Github Skills (42)
data-migration10
javascript10
postgresql10
build-definition10
admin10
back-end-development10
python10
elixir10
mapbox-gl10
testing10
databases10
psycopg10
typescript10
typescript-definitions10
database-administration10
Programming languages (22)
Github contributions (5)
PostHog/posthog-js
Oct 2020 - Jan 2023
Send usage data from your web app or site to PostHog, with autocapture.
Role in this project:
Full-stack Developer
Full-stack DeveloperContributions:140 reviews, 321 commits, 112 PRs in 2 years 3 months
Contributions summary:Karl-aksel implemented and improved session recording features within the PostHog-js library. Their work involved extracting and refactoring utility functions for loading scripts, integrating the rrweb recorder, and emitting events for session snapshots. They also worked on incorporating configurations to control session recording, including enabling/disabling it via the `/decide` endpoint and starting recording based on return values. Furthermore, they updated tests, improved the event structure, and addressed code documentation.
analyticsjavascriptnpmusage-datatypescript
PostHog/posthog
Jun 2020 - Jan 2023
🦔 PostHog provides open-source web & product analytics, session recording, feature flagging and A/B testing that you can self-host. Get started - free.
Role in this project:Backend & Data Engineer
Backend & Data EngineerContributions:2514 reviews, 1246 commits, 1635 PRs in 2 years 7 months
Contributions summary:Karl-aksel primarily focused on the ClickHouse database, developing and maintaining its integration with the PostHog platform. They implemented a benchmarking suite for ClickHouse queries, significantly enhancing the system's performance testing capabilities. The user also addressed issues related to the performance of the user's queries and introduced code improvements in the system and created metrics and graphs to help understand the performance. Additionally, the user worked on integrating group analytics and making several updates and improvements to the overall infrastructure.
pythonabtestingdata-warehouseself-hostjavascript
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