Senior Software Engineer - Database team

We’re Capital on Tap Capital on Tap started because small businesses were underserved. Big banks were slow, their products weren’t fit for purpose, and small business owners often couldn’t access what they needed. We set out to fix that. Today we’re a financial platform — not just a credit card company. We offer a best-in-class business credit card, SME-focused spend management platform, a savings product that hit £1 billion in funds within its first year, and a growing suite of tools and financial products that make running a small business easier.

1,000+ employees, £20bn in annual card spend, 200,000+ customers, 17,000+ Trustpilot reviews averaging 4.7 stars, and we’re profitable. We’ve done a pretty good job so far, but we’re just getting started!

We’re hiring our first dedicated Database Performance Engineer to own performance and scale. This role works from our Moorgate (London) Offices 2 days per week.

• Evangelise advanced database technologies to the software engineering teams.
• Research, demo and promote technologies such as graph databases and zero-downtime data migrations, and how they can be used in EF via C#.
• Own query and index performance across our transactional SQL Server estate, using execution plans, Query Store, wait statistics, real production telemetry or other data driven measures.
• Investigate and implement horizontal scaling techniques such as multi-cluster architecture, contained availability groups, sharding, etc, to ensure Capital on Tap’s distributed software estate can continue to support a fast growing customer base and increasing service count.
• Find and remove the bottlenecks on our latency critical paths, starting with card authorisation and ledger read/writes, and hold them to an agreed p99 budget.
• Own high availability and disaster recovery. Availability groups, failover, backup and restore testing against real RTO and RPO targets, and the runbooks that go with them.
• Build and enhance self serve tooling to enable development teams to identify query plan regressions along with self service diagnostic tools to allow teams to debug their own query performance.
• Automate what is currently manual, using Power Shell or Terraform and treat database configuration as code.
• Manage SQL Server cost as a first-class metric alongside latency and uptime.
• Work alongside Product Engineering and our data analytics team, reviewing designs before they ship and levelling up how the whole engineering org thinks about data access.

• Experience working with ORMs (ideally Entity Framework) and the particular performance tradeoffs that come with an ORM.
• Substantial experience running Microsoft SQL Server in production at scale, whether that be self managed, Managed Instances, or on Azure SQL, in a business where downtime and latency have direct commercial impact.
• Real depth in the internals. The query optimiser and plan cache, indexing and statistics, locking, blocking and isolation levels, tempdb, and the wait types that tell you which of those is actually hurting you.
• A track record of specific, measurable performance wins you can walk us through end to end.
• Experience scaling relational data past the point where tuning alone works. Partitioning, archival, denormalisation, caching, read replicas, or a considered move to a different store.
• Comfortable writing application code, not just scripts. T-SQL to an expert level, plus Power Shell, and infrastructure as code.
• Hands-on with HA/DR design and with leading production incidents.
• Working knowledge of other database engines such as PostgreSQL, and views on the relative pros/cons.
• An ability to translate technical concepts and tradeoffs to non-database specialists.

We welcome,…