About the role
The Sync team builds the engine that keeps every client, person and agent looking at the same document, task list and calendar at the same moment. Edits arrive from phones on flaky networks, from browser tabs left open for a week, and from agents writing dozens of changes a second, and all of them must converge without losing anyone's work.
Sync sits underneath Clexerl Go and feeds every surface in it. Its choices about ordering, causality and offline storage decide how fast an agent's change appears on a person's screen and whether a conflict can be explained afterwards. Frontier AI's long-horizon agents depend on the same guarantees, so this team's correctness work is shared with the agent runtime.
What you’ll do
- Implement and maintain CRDT-based document and list types, including their merge, compaction and garbage collection.
- Design the wire protocol for deltas, acknowledgements and resumption after long disconnects.
- Build server-side ordering and fan-out services that hold p99 latency under 150 milliseconds at peak load.
- Write property-based and fuzz tests that replay adversarial interleavings, and keep them in continuous integration.
- Instrument convergence lag and conflict rates, and turn regressions into post-mortems with clear owners.
- Work with the client teams on offline storage, retry behaviour and the cost of each sync round trip.
What you’ll bring
- Experience designing distributed systems with replication, ordering guarantees or consensus protocols.
- Working knowledge of CRDTs, operational transforms or other approaches to merging concurrent edits.
- Strong systems programming in Go, Rust or a similar language, with careful attention to concurrency.
- Familiarity with WebSockets, HTTP/2 streams and the failure modes of long-lived connections.
- A track record of debugging production incidents in stateful services, and writing down what was learned.
- Comfort reasoning about time, clocks and causality in code that runs on many devices.
Nice to have
- Experience with local-first databases, SQLite on mobile or client-side storage engines.
- Background in collaborative editors, text editing data structures or version control internals.
- Knowledge of formal specification tools such as TLA+ for checking protocol designs.
- Work on end-to-end encryption for multi-device sync, including key rotation and recovery.
Work you might take on
- 01
Build a replay harness that reruns recorded client traffic against a candidate sync build and reports divergent documents.
- 02
Add compaction to the task list type so that long-lived documents stay small on disk and on the wire.
- 03
Prototype presence indicators for agents, showing which item an agent is reading or changing and when it last acted.
- 04
Write a TLA+ model of the reconnect handshake and use it to find a lost-update case before release.
Compensation
$220K – $340K
The US base salary range for this role. Every offer also includes equity in Clexerl and, when it spins out, in the venture you help build. We tell you the reasoning behind your number.
Benefits
Health, fully covered
Medical, dental and vision for you and your dependants, premiums paid in full.
Two kinds of equity
Equity in Clexerl, plus a stake in the venture you help build when it spins out.
22 weeks parental leave
Fully paid, for every parent, however your family arrives.
Rest that sticks
Flexible time off with a four-week minimum we actually check on, plus a company-wide week in December.
Learning and compute
A yearly budget for courses, conferences and books, and compute credits for side projects.
401(k) with a 4% match
Matched from your first paycheque and vested immediately.
How we hire
Apply 5 minutes
Send links to what you have built and a few lines on why this role. No cover letter needed.
Intro call 30 minutes
A conversation with the hiring manager about the work, the team and what you want next.
Work sample 2–4 hours
A paid take-home or a pairing session on a real-shaped problem. You pick the format.
Studio day One day
Meet the team, go deep on your work and ours. Remote or in person.
Offer Within 5 days
A written offer with the full range, the equity and the reasoning behind both.
Opens an email with a short template. Links beat résumés.