BREAKING
RUST ECOSYSTEM LEGEND PREDRAG GRUEVSKI MAKES SEMVER VIOLATIONS A THING OF THE PAST  •  cargo-semver-checks HEADING INTO CARGO CORE  •  TRUSTFALL: QUERY ANYTHING, ANYWHERE, IN ANY COMBINATION  •  MIT OLYMPIAD MEDALIST TURNED OPEN-SOURCE CORNERSTONE  •  OBI1KENOBI ON GITHUB - THE FORCE IS STRONG WITH THIS ONE  •  SPOKE AT RUSTCONF 2024, EURORUST 2024, FOSDEM 2024  •  RUST FOUNDATION BACKS PREDRAG'S SEMVER MISSION  •  CORRECTNESS. ERGONOMICS. PERFORMANCE. IN THAT ORDER.  •  RUST ECOSYSTEM LEGEND PREDRAG GRUEVSKI MAKES SEMVER VIOLATIONS A THING OF THE PAST  •  cargo-semver-checks HEADING INTO CARGO CORE  •  TRUSTFALL: QUERY ANYTHING, ANYWHERE, IN ANY COMBINATION  •  MIT OLYMPIAD MEDALIST TURNED OPEN-SOURCE CORNERSTONE  • 
Predrag Gruevski
RUST ENGINEER & API DESIGNER

Predrag
Gruevski

The person making sure your Rust packages don't quietly break everything downstream.

Independent software engineer. Creator of Trustfall and cargo-semver-checks. MIT alum. International math and programming olympiad medalist. Former principal engineer at Kensho Technologies. The kind of person who asks "what if we could query absolutely anything?" - and then builds the answer.

Rust API Design Open Source Query Engines Compiler Tech SemVer
5 Olympiad Medals
2 Cornerstone OSS Tools
500x Performance Gains
MIT CS & Engineering
Sources Trustfall Can Query

He Doesn't Ship Bugs. He Ships Tools That Prevent Them.

Predrag Gruevski is the rare engineer whose work is most visible when nothing goes wrong. His cargo-semver-checks tool sits quietly in the Rust ecosystem, catching the kind of breaking changes that used to ripple through dependency graphs like a dropped stone in a pond - silently, invisibly, until production exploded. That's not an accident. That's a design philosophy made into software.

Before he was the person making semantic versioning a solvable problem, he was a teenager winning medals at the International Mathematics Olympiad and the International Olympiad in Informatics in the same years. Not one. Both. The precision that earns you a bronze in pure mathematics and another in competitive programming is exactly the same precision that turns into an obsession with correctness-first software development.

He took that precision to MIT, graduated with a B.S. in Computer Science and Engineering in 2015, and spent the following years at the kind of companies that attract people who think in systems: Dropbox, Firebase (weeks before Google bought it), Palantir, and ultimately Kensho Technologies, where he climbed from engineer to principal architect. Along the way he shipped an open-source GraphQL compiler, got listed on multiple patents, and led teams that demonstrated something he genuinely believes: hiring and mentoring early-career engineers builds stronger, more diverse teams than hunting exclusively for senior talent.

Then he left Kensho to go independent. Not because things were bad, but because he had questions that needed answering - and tools that needed building.

Software correctness, ergonomics, and performance - in that order.

- Predrag Gruevski, on his engineering priorities

Two Tools. Infinite Scope.

Trustfall A universal query engine
Rust Query Engine WebAssembly

What happens if you could query anything - APIs, files, databases, LLMs - using the same query language? Predrag asked that question and then built the answer. Trustfall is a library that makes heterogeneous data querying composable and correct. It even runs in-browser as WebAssembly.

The insight behind Trustfall is a database concept applied to a compiler-adjacent domain: instead of teaching each tool to fetch data its own way, give everything a unified query interface. The result is a platform for building tools that would otherwise require months of custom plumbing.

cargo-semver-checks Semantic versioning linter
Rust Cargo SemVer

Accidental breaking changes in Rust library APIs cause downstream chaos. cargo-semver-checks catches them before they ship. Adopted by the tokio runtime and other heavyweight crates, it's now under consideration for integration directly into cargo - the Rust build tool every developer uses.

The Rust Foundation has backed its development. Recent optimization work delivered 100-500x speedups on specific operations. It runs on Trustfall under the hood, making the design as principled as the mission.

GraphQL Compiler Open-sourced from Kensho
GraphQL Compiler Database

At Kensho, Predrag led the team that compiled GraphQL into database queries - treating a query language as a target for a compiler rather than a runtime interpreter problem. The results shipped as open source and influenced how the field thinks about GraphQL at scale.

The project was emblematic of his wider approach: reach for the abstraction that eliminates the class of bugs, not the patch that fixes the specific one.

The Engineering Philosophy

01
Correctness
Wrong code that performs well is still wrong. Ship the right answer first, then make it fast.
02
Ergonomics
A correct API that nobody can use correctly is just a sophisticated footgun. Design matters.
03
Performance
Fast matters. But it's third. Measure twice, optimize once, never as a substitute for correctness.

Stories That Don't Fit in a README

PANEL 01
Beast Mode Unlocked

At Dropbox's internal Hack Week, Predrag built a pool-shot coach using machine vision. It won him the runner-up "Beast Mode" award. The man pointed a camera at a billiards table and taught it physics. For fun. During an internship.

PANEL 02
The MIT Security Caper

As a computer systems security class project at MIT, Predrag and teammates discovered real vulnerabilities in 6 popular PC remote control apps with 2-7.5 million downloads each. Homework with consequences. The responsible kind.

PANEL 03
Obi-Wan Commits Code

His GitHub username is obi1kenobi. As in Obi-Wan Kenobi. Every PR he merges, every issue he closes, every release he ships - technically authored by a Jedi master. The force is strongly typed.

PANEL 04
Watched a Rocket Explode

Self-described "huge space nerd." Went to witness a giant rocket explode in person. Also loves The Expanse. Also plays ice hockey. Also skis. The man contains multitudes and knows how to fall dramatically in multiple disciplines.

PANEL 05
9-13x Faster, By Homework

For a performance engineering class at MIT, Predrag achieved 9-13x faster graph processing than the prior state of the art. Not a paper. Not a PhD. A class project. The bar was already the state of the art.

PANEL 06
Firebase, Days Before Google

He interned at Firebase - just before Google acquired it. Front-row seat to one of the more consequential acquisitions in developer tooling history. He left a job at a startup. Google found it weeks later.

OLYMPIAN ORIGINS

He Competed at the Highest Level in Two Disciplines Simultaneously

Most competitive programmers focus on algorithms. Most competitive mathematicians focus on proofs. Predrag medaled internationally at both in overlapping years. The International Mathematics Olympiad and the International Olympiad in Informatics are each brutally selective - national teams, months of preparation, problems that stump professors. He did both. Won medals at both. Then went to MIT.

🥉 IMO 2009 International Mathematics Olympiad - Bronze
🥇 Balkan MO 2010 Balkan Mathematical Olympiad - First Place
🥉 IOI 2010 Int'l Olympiad in Informatics - Bronze
🥉 IMO 2011 International Mathematics Olympiad - Bronze
🥇 Balkan MO 2011 Balkan Mathematical Olympiad - First Place
🥉 IOI 2011 Int'l Olympiad in Informatics - Bronze
ON STAGE

He Shows His Work in Public

Predrag writes, speaks, and appears on podcasts about the technical problems he's solving - not as promotion, but because the ideas genuinely deserve circulation. RustConf, EuroRust, FOSDEM - he turns up where the community is and explains what's hard about what he's doing.

  • RUSTCONF 2024 - MONTREAL
    Putting an End to Accidental SemVer-Breaking Changes
    Watch on YouTube →
  • EURORUST 2024
    Build Bigger in Less Time: Code Testing Beyond the Basics
    Watch on YouTube →
  • FOSDEM 2024
    Open Source & Rust Ecosystem Talk
    Speaker Profile →
  • DEVELOPER VOICES PODCAST
    A Universal Query Engine in Rust (with Predrag Gruevski)
    Listen / Watch →
  • RUSTSHIP PODCAST #2
    Trustfall and cargo-semver-checks with Predrag Gruevski
    Watch on YouTube →
  • DEVTOOLS.FM EPISODE #113
    Trustfall, Cargo Semver Checks, and the Future of Query-Based Tools
    Listen →
  • OPEN SOURCE SECURITY PODCAST - APRIL 2025
    cargo-semver-checks with Predrag Gruevski
    Listen →

What happens if we can query absolutely anything?

- The question behind Trustfall
CAREER ARC

From Olympiad Podiums to Open-Source Bedrock

2009-2011
International Math Olympiad bronze medals (2009, 2011). International Olympiad in Informatics bronze medals (2010, 2011). Balkan Math Olympiad first place twice. Competing at the highest levels of both disciplines simultaneously.
2011-2015
MIT - B.S. Computer Science and Engineering. Performance engineering research achieving 9-13x graph processing speedups. Security research exposing vulnerabilities in apps with millions of users. Member of MIT's computer security CTF team. Internships at Dropbox (Beast Mode award), Firebase (pre-Google), and Palantir.
2015-2022
Kensho Technologies: engineer to principal architect. Led Graph Infrastructure and Query Infrastructure teams. Shipped open-source GraphQL compiler. Open-sourced pytest-annotate. Multiple patents. Advocated for and proved the value of early-career hiring in building diverse, effective engineering teams.
2022
Created and launched Trustfall - a universal query engine - and cargo-semver-checks, a semantic versioning linter for Rust. Both projects built on each other: cargo-semver-checks runs on Trustfall under the hood.
2023
Went independent. cargo-semver-checks adopted by tokio and major Rust crates. Rust Foundation provides funding for development. RustShip Podcast appearance. The open-source bet is paying off.
2024-2025
RustConf 2024 (Montreal), EuroRust 2024, FOSDEM 2024. 100-500x performance improvements to cargo-semver-checks. cargo team evaluating integration into cargo itself. Continued work toward a Rust ecosystem where breaking changes can't accidentally ship. Appeared on Open Source Security Podcast (April 2025).