Hire Cassandra developers

The honest answer is: it depends on the half-life of your Cassandra surface area. If your roadmap leans heavily on partition keys and clustering columns designed for access patterns and you expect to keep investing in ScyllaDB over the next 18-24 months, a specialist will out-deliver a generalist on day-30 throughput and incident response.

If your team is smaller than ten engineers, or Cassandra is one of three or four core technologies, hire a strong generalist who has shipped Cassandra in anger at least twice. The cross-stack pattern recognition will pay for itself the first time you need to integrate CQL with another part of the system.

On Haystack we surface both - filtered by whether the candidate self-identifies as a Cassandra specialist and verified against their last two roles. Expect to pay around £75k–£100k for a mid-level UK hire, scaling toward £105k–£150k for senior.

A great Cassandra engineer is not the one with the most stars on GitHub - it is the one who has paged at 3am for a Cassandra service they wrote, and changed how they build because of it. Across the platform and product-engineering hires we have placed in 2025-2026, the same patterns keep showing up.

Every stack has its own pattern of plausible-sounding answers that fall apart in production. With Cassandra, these are the patterns that most often correlate with a six-month regret hire on the employer side.

When teams ask us how to evaluate Cassandra engineers beyond a CV, we recommend a 90-minute paid take-home that mirrors real work, not algorithm puzzles. The brief below is one we have refined with employers hiring platform and product-engineering teams.

Give the candidate a small, intentionally imperfect Cassandra service that already does partition keys and clustering columns designed for access patterns. Their task is to add a second capability - multi-dc clusters with sensible consistency settings - while keeping existing behaviour green. Grade in three parts.

By week one, the new Cassandra engineer should have shipped a small change to production - typically a docs fix, a ScyllaDB dependency bump or a minor refactor in partition keys and clustering columns designed for access patterns. The goal is to validate the development loop, not to ship anything heroic.

By week two, expect them on the on-call rota in a shadow capacity, pair-programming on at least one feature, and asking pointed questions about why specific Cassandra patterns were chosen. If they are not asking those questions, the hire is going to plateau.

By day 30, they should own one cleanly-scoped slice of the Cassandra surface area, have a public ramp-up document, and be the named reviewer on PRs touching that area. Every Haystack employer gets a structured onboarding template - so you are not reinventing the playbook for each hire.