Software Engineer

Julius Brussee

Building tools that respect your time.

Projects

The Caveman Ecosystem5 repos · 102,840★

One idea — say more with fewer tokens — compounded into five open-source products: a skill, a workflow, a memory layer, a terminal agent, and a fine-tuned model.

Building nowthe company
Side projects

About

Everyone's racing to build better AI models. I build the tooling around them. Caveman, my Claude Code skill that strips ~65% of an agent's tokens without losing accuracy, hit #1 on Hacker News and crossed 70,000 GitHub stars. It now anchors a pack of seven agent skills I ship as one npm install.

I'm also a founding engineer at Stacklink, an enterprise RAG platform, and I'm building Revu, a macOS study app that brings spaced repetition and multi-agent AI to studying. Both share an instinct I keep coming back to: build things that get better the more you use them. Stacklink's search sharpens with every document you give it; Revu learns what you actually forget and schedules around it.

I study Data Science & AI at Leiden University, where I sit on the Education Committee and help shape the curriculum. I write about building AI systems and shipping indie software on Polder, my Substack.

Education

BSc

2025 — Present

Data Science and Artificial Intelligence

Leiden UniversityLIACS

  • Education Committee member — shaping curriculum for DS&AI
  • Focus areas: machine learning, NLP, multi-agent systems
  • Building AI-native tools alongside coursework

Currently

Caveman is at 99,984 GitHub stars and approaching 100,000 — the full ecosystem crossed 102,000 across caveman, cavekit, cavemem, caveman-code, and cavegemma. Elasticsearch Labs shipped elastic-caveman this week, showing 64% token reduction across eight real Elasticsearch scenarios. Maintaining the codebase, triaging issues, and shipping new modes. Heads-down on Stacklink: building the incremental sync pipeline and hybrid retrieval layer for the TU Eindhoven Innovation Contest. Cavekit, Revu, and Polder posts in parallel.

Last updated 2026-08-21

Press

Caveman in the wild

Article · Elasticsearch Labs · Aug 2026

Elastic-caveman for token reduction with Claude

Elasticsearch Labs tested a Caveman-inspired agent skill across eight real Elasticsearch scenarios: 64% average token reduction with zero accuracy loss and full ES|QL syntax preservation.

Article · TechTimes · Jul 2026

JetBrains Tests Caveman Token Skill on 86 Real Tasks: Savings Hit 9%, Not 65%

TechTimes covered the JetBrains 86-task paired benchmark of Caveman on Claude Code: 8.5–9% measured output-token reduction on real agentic tasks, with no quality degradation.

Article · InfoWorld · Jul 2026

'Talk like a caveman' prompts save tokens, but far less than promised

InfoWorld covered the JetBrains benchmark showing Caveman cuts output tokens by 8.5% on real agentic tasks — far less than the 65% headline, but with no quality degradation.

Article · JetBrains · Jul 2026

Speaking to AI Agents like Cavemen Saves 65% of Tokens. We Test.

JetBrains ran an 82-task paired A/B benchmark of Caveman on SkillsBench: 8.5% measured output-token reduction with no statistically significant impact on task success or code quality.

Social · Leiden University · Jun 2026

Leiden University spotlights Caveman

Julius's own faculty shared Caveman with their network — the student-built tool making AI coding agents dramatically leaner.

Broadcast · RTL · Editie NL · May 2026

Caveman on RTL Editie NL

RTL's Editie NL covered the Leiden student behind Caveman and the “primitive language” trick that trims AI token use by ~65%.

Broadcast · BNR Nieuwsradio · May 2026

Nederlandse student (19) verrast AI-bedrijven: ‘Niemand dacht aan deze simpele oplossing’

BNR's tech desk featured Caveman — the “primitive language” that cuts AI token use by ~65% and went viral on GitHub, drawing attention from NVIDIA and others.

Talk · AI House Amsterdam · Prosus · May 2026

Lunch & Learn: Caveman at AI House Amsterdam

Julius gave a Lunch & Learn talk on Caveman at AI House Amsterdam, Prosus's AI community hub, walking through the token-compression approach.

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