Senior Software Engineer - Database team

Engg

Greater London

Hybrid

GBP 80,000 - 110,000

Full time

10 days ago

Application generator

Don’t send a generic resume — generate a resume and cover letter tailored to this exact role.

Get past ATS filters

Benefits offered by this job

Private Healthcare

Worldwide travel insurance

Anniversary Rewards

Salary Sacrifice Pension

Octopus EV Salary Sacrifice

28 days holiday

Learning and Wellbeing Budget

Parental Leave

Cycle to Work

Season Ticket Loan

Therapy sessions

Dog Friendly Offices

Free drinks and snacks

Job summary

Capital on Tap is hiring a Database Performance Engineer to own performance and scale. This hybrid role works from our Moorgate offices two days per week and involves optimizing SQL Server performance, migrations, and architecture decisions.

You will partner with engineering and analytics, drive high availability and disaster recovery, and implement automation with PowerShell and Terraform. Strong EF ORM and SQL Server expertise are essential.

Qualifications

Experience with ORMs and performance tradeoffs.
Substantial production SQL Server experience at scale.
Deep understanding of query optimiser, plan cache, indexing, stats and wait types.
Proven ability to drive end-to-end performance improvements.
Experience with scaling relational data and read replicas.

Responsibilities

Evangelise advanced database technologies to software teams.
Demonstrate and promote graph DB tech and zero-downtime migrations in EF/C#.
Own query and index performance across SQL Server estate.
Implement horizontal scaling like multi-cluster, AGs, sharding.
Identify bottlenecks on latency-critical paths and reduce p99 latency.
Own HA/DR design with RTO/RPO targets and runbooks.
Build self-serve tooling to diagnose query performance.
Automate config with PowerShell or Terraform.

Skills

ORMs (Entity Framework)

SQL performance tuning

HA/DR design

Data architectures

Query plan analysis

Infra as code

Education

Tools

SQL Server

Azure SQL

PostgreSQL

PowerShell

Terraform

Job description

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!

Hybrid role

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.

What You'll Do

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 PowerShell 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.

What We’ll Be Looking For

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 PowerShell, 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.

Diversity & Inclusion

We welcome, consider and encourage applications from anyone who shares our commitment to inclusivity. Join us in creating a space where authenticity thrives, and everyone can do their best work.

Great Work Deserves Great Perks