Senior Database Engineer New London

Capital on Tap

Greater London

Hybrid

GBP 85,000 - 110,000

Full time

23 hours ago

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Benefits offered by this job

Private Healthcare (Vitality)

Worldwide travel insurance

Sabbatical program

Pension: Salary Sacrifice

28 days holiday

Learning & Wellbeing Budget

Enhanced Parental Leave

Cycle to Work

Season Ticket Loan

Therapy sessions

Dog-friendly office

Free drinks and snacks

Job summary

Capital on Tap is hiring a Database Engineer to own performance and scale for SQL Server on Azure. You will lead improvements to latency, cost and reliability, working with a small team of DBAs and SREs in a senior IC role.

You’ll drive high-availability design, automate tooling, and collaborate with product engineering and analytics to shape data access across the platform.

Qualifications

Substantial experience running Microsoft SQL Server in production at scale.
Deep knowledge of the query optimiser, plan cache, indexing, statistics, and wait types.
Proven ability to deliver end-to-end performance improvements.
Experience scaling relational data beyond tuning techniques (partitioning, archiving, caching, replicas).
Proficient in T-SQL; skilled with PowerShell or Python and infrastructure as code.
Hands-on HA/DR design and managing production incidents.
Experience with ORMs (Entity Framework) and related tradeoffs.
Experience with PostgreSQL and other engines; ability to compare pros/cons.
Ability to communicate technical concepts to non-database specialists.

Responsibilities

Own query and index performance across our SQL Server estate using plans and telemetry.
Investigate horizontal scaling like multi-cluster architecture, AGs, and sharding.
Identify bottlenecks in latency-critical paths (card authorisation, ledger reads/writes).
Own high availability and disaster recovery, runbooks, RTO/RPO targets.
Build self-serve tooling to detect query plan regressions and diagnose issues.
Automate manual tasks with PowerShell, Python, or Terraform; treat DB config as code.
Manage SQL Server cost as a first-class metric alongside latency and uptime.
Collaborate with Product Engineering and data analytics to review designs.

Skills

SQL Server

Performance tuning

T-SQL

Python

PowerShell

Terraform

Azure

Entity Framework

PostgreSQL

Infrastructure as code

Education

Bachelor’s degree or equivalent

Tools

SQL Server Management Studio

Query Store

Azure SQL

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!

London, Old Street | 2 Days in Office

Database Engineering at Capital on Tap

Our platform runs on .NET and SQL Server on Azure, and it has grown a long way past what it was originally designed for. We are hiring our first dedicated database performance engineer to own performance and scale: to make the fast paths fast, to keep them fast as volume grows, and to give every engineer here the tooling and the judgement to write data access that holds up in production.You will join a small agile team comprising DBAs and site reliability engineers in a hands‑on senior individual contributor role. You will not be a ticket queue. You will pick the work that moves latency, cost and reliability, and you will be trusted to say what needs re-architecting.

What You'll Do

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, Python, 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.

Our Values & Culture

Just Pilot: We never settle for “good enough”. We pilot new ideas fast, ask questions to figure it out, and scale quickly.
Why Not Today? Fast is as slow as we go - speed and simplicity gives us a competitive advantage.
Be a Buddy: We tap in from day one to help the team, we do the right thing even if it’s hard.
Owners and Dates: We don’t chase people. If you own a task and agree to a date, the expectation is that it gets done.
Feedback: We want our employees to flourish, so we regularly provide direct and constructive feedback.

What We're Looking For

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 or Python, and infrastructure as code.
Hands‑on with HA/DR design and with leading production incidents.
Experience working with ORMs (ideally Entity Framework) and the particular performance tradeoffs that come with an ORM.
Experience working with 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.
30 minute screening with a talent partner
45 minute tech chat with Hiring Manager
90 minute technical interview
30 minute values interview with Head of Platform Engineering

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

We try not to take ourselves too seriously (all the time) so we make sure our office is decked out with a pool table, arcade machine, beer tap, and a couple of office dogs thrown in for good measure. Check out our benefits: