Full Stack Software Engineer, StackOne
£72-110k
OTE
£65-100k
BASE
+ 0.04% – 0.08% Equity
2 days a week in office
Unified API for B2B SaaS
Be an early applicant
Unified API for B2B SaaS
21-100 employees
Be an early applicant
£72-110k
OTE
£65-100k
BASE
+ 0.04% – 0.08% Equity
2 days a week in office
21-100 employees
Company mission
To empower SaaS companies to build groundbreaking products that seamlessly connect with their customers’ stacks.
Role
Who you are
- Proven experience as a full-stack engineer shipping user-facing, backend-heavy systems
- Expertise in TypeScript and solid experience with React; comfortable building clean UIs for complex backend capabilities
- Strong background designing and operating public APIs and multi-tenant systems
- Experience with distributed systems concepts: streams, queues, idempotency, consistency, and performance trade-offs
- Ability to think in systems (throughput, tail latency, failure modes) and explain trade-offs clearly
- Curiosity and pragmatism with LLMs/agents: know when they help, and how to guardrail/evaluate them
- Desire to work in a fast-paced startup, take ownership end-to-end, and bias toward shipping
- (Preferred) Experience publishing CLIs & SDKs (internal or open-source)
What the job involves
- We are looking for a Software Engineer with a strong background in AI production-grade applications with professional experience working with LLMs (eg: GPT, Anthropic and others)
- In this role, you will deliver AI features and products end-to-end and work with the wider AI team of StackOne (comprising of AI researchers and other AI engineers)
- You will report directly to the CTO
- Act as a full-stack web application engineering: ideate, build, and ship features across frontend, backend, data, and infrastructure
- Model data & schemas across SQL, document/columnar stores, and OLAP; design for correctness, performance, and cost
- Design and evolve public APIs and standards: REST contracts, OpenAPI, pagination, auth, error models, plus MCP/tool-calling conventions
- Engineer for scale and resilience: rate limiting, retries, idempotency, back-pressure, caching, SLIs/SLOs, and safe fallbacks
- Build and operate event systems with Kafka-class streaming patterns: producers/consumers, partitioning, DLQs, reprocessing, schema evolution
- Raise observability & reliability: tracing, metrics, logs, alerting, zero-downtime deploys, runbooks
- Leverage LLMs/agents to accelerate development while maintaining reliability, testing, and code quality
- Infra & monitoring: AWS (ECS, RDS, Elasticache, Lambda etc.), Cloudflare, Tinybird, Modal, Dagster, Langsmith, Datadog, Sentry, Incident.io
- Languages & Frameworks: Typescript (Node.js), Python, NestJS, React, Svelte,
- Other day-to-day Tools: Postman, Notion, Slack, Jira, Github and more
Salary benchmarks
Our take
The explosion of SaaS tools has created an integration nightmare for companies. More and more B2B customers are expecting their SaaS tools to integrate with each other natively. But building and managing API connections in-house as a software vendor is time-consuming and costly, diverting teams from their core roadmap and stopping sales teams from selling.
As the next-generation integration platform, StackOne is solving the challenge of building SaaS integrations at scale once and for all. Founded in 2023 by ex-Google and Oracle executives, StackOne has seen exceptionally fast growth since its launch. With its best-in-class security and real-time architecture, the company is well-positioned to become a category leader in the API integration solutions market.
Steph
Company Specialist at Welcome to the Jungle
Insights
Company
Employee endorsements
Hard working team
"Each team member is approachable and happy to help, contribute or answer questions. There's a great sense of unity toward a common goal, and I trust..."
Funding (last 2 of 3 rounds)
Apr 2025
$20m
Series A
Nov 2023
$3.6m
Seed
Total funding: $23.9m
Company benefits
- Participation in the company’s employee share options plan
- 25 days holiday + 1 additional day holiday per year of tenure
- Remote working friendly
- £1,000 for your home office set up + £500/year top-up
- Cycle2Work and Electric Car Scheme
- Multiple company offsites per year
- Private health insurance (including dental & optical)
- Health, fitness and gift card discounts
- Annual team offsite to sunny spots (last ones were in Spain and Portugal)
Company HQ
Central London
Articles
Leadership
Romain Sestier
(Co-Founder & CEO)Previously worked for Google as co-founder and Product Lead of Area120, VP of Product and Sales at Yieldify, co-founder and CEO of Upper.ai and Head of UK Professional Services at ContentSquare.
Guillaume Lebedel
(Co-Founder & CTO)Previously VP of Engineering at Yieldify until its acquisition by Epsilon/Publicis. Also co-founded another start-up and worked at Maxymiser (acq. by Oracle) as a developer.
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