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Backend Engineer, Infrastructure

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TEAM

Engineering

TYPE

Full-time

LOCATION

London (Hybrid, 4 days in-office)

ABOUT 36 LABS

36 Labs is a seed-stage startup that started out of the UCL Machine Learning lab.

We bootstrapped to 10 people, and now we're on the next leg of growth.

AI can generate almost any media, but it still can't judge what wins human

attention. AI-generated content on social platforms is growing fast, and we think

every creative workflow will be agent-assisted or fully agentic within a few years.

Our work is improving how models reason about creative decisions, learning from

how real audiences respond to the content we make.

THE ROLE

You'll own our core platform: deployment, service communication, job

orchestration, and the APIs and database that our products depend on as we scale

throughput 100x over the next year.

You'll have the autonomy to shape the platform's infrastructure, with scope to grow

into technical leadership. You'll work closely with the CTO on architecture, with

machine learning engineers to develop and implement our "creative harness", and

with content engineers to improve its capabilities.

WHAT YOU'LL DO

WHAT WE'RE LOOKING FOR

Design system architecture: service boundaries, data and API contracts, and

service-to-service communication.

Lead the migration from Railway to Cloudflare: target architecture, migration

plan, cutover and decommissioning, with no disruption to production workloads.

Own deployments and production health across our services: CI/CD,

environments, rollbacks, secrets, observability and feature flags, fixing issues at

the cause and turning them into alerts, runbooks and better defaults.

Own the scheduler, queues and sandboxes behind our long-running, multi-step

work, building recovery, end-to-end traceability, and cost and latency efficiency.

Build reliable, well-documented internal APIs: simple, durable primitives that the

rest of the team, downstream products and our agents build on top of.

Own our data platform, including schema design, migrations and performance at

scale.

Set the standard for backend engineering and own the vision for our software

factory: design and code quality, documentation, and the guardrails that enable

the team to ship high-quality code at speed.

NICE TO HAVE

BSc in Computer Science, Engineering, Mathematics, Statistics, or the

equivalent in the form of experience. Experience writing production Python and

TypeScript.

4+ years building and running backend systems in production, including how

they were deployed and operated.

Strong experience building job and workflow systems in production, with sound

judgment on idempotency, retries and back-off, concurrency and parallelism.

Strong experience running relational databases in production, ideally Postgres,

including schema design, migrations on live data and query performance.

Built infrastructure from scratch, scaled it through rapid growth in load, and led

at least one significant platform migration.

Owned infrastructure end to end: containers, CI/CD, networking, observability,

incidents.

Led technical work: set direction, reviewed designs, mentored.

Taken complex systems from ambiguous problem statements to reliable

production services, including APIs that remained reliable as load and

consumers grew.

Systems or projects you've built and can discuss in technical depth.

Used Cloudflare in production: Workers, Queues, Workflows, Durable Objects, R2

or Containers.

Event-driven systems: event streams, outbox patterns, webhooks.

Browser and mobile OS automation at scale (Playwright, Puppeteer, CDP,

Appium, ADB), including IP management, proxies and fleets of workers, VMs or

devices.

OUR STACK

Python (FastAPI, SQLAlchemy, Alembic), TypeScript, Postgres, Docker, GitHub

Actions, Sentry, LLM and generative media APIs.

We encourage you to apply even if your experience doesn't match every line

above.

Founding or early engineer at a startup, or equivalent ownership inside a larger

company.

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WHY ARE YOU THE RIGHT FIT?

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Senior Backend Engineer Location: Remote within the UK, with occasional in-person meetups in London

Type: Full-time

Salary: £70,000-80,000, depending on experience

About the Role

We are looking for a senior backend engineer to help turn our AI assessment capabilities into reliable, scalable product infrastructure. You will build the systems behind customer- facing assessment workflows and help customers integrate sAInaptic into their existing learning and assessment platforms.

This is a hands-on individual-contributor role with substantial ownership of backend delivery. You will work alongside our senior full-stack architect, AI engineers and product team, taking responsibility for turning technical decisions into robust production systems and helping spread implementation and operational knowledge as the company grows. In a small team, your work will have a direct and visible impact on how customers integrate with our platform and how reliably our AI assessment capabilities operate at scale.

About Us

sAInaptic is building an AI-powered multimodal assessment platform.

We’re transforming how assessments are designed, delivered, marked and quality assured through an AI-enabled platform and API for awarding organisations, training providers, employers and educational institutions.

Our AI has already marked millions of free-text responses, saved thousands of marking hours, and delivered savings of more than £150,000 per organisation for individual customers.

sAInaptic was founded by a team of educators and data scientists. We’ve grown from five to nine people in the last 12 months and, following our seed round, are investing in the scalable platform that will support our next phase of growth.

What You’ll Do • Build and maintain Python backend services and customer-facing APIs, primarily

using FastAPI. • Build and extend integrations with learning management systems and other third-

party platforms, including integrations using LTI 1.3. • Design and maintain database-backed workflows using PostgreSQL, SQLAlchemy

and Alembic. • Build reliable asynchronous processing for AI assessment work, including

persistence, queues, retries, batching and status tracking. • Support secure customer onboarding through authentication, authorisation,

customer-specific configuration and integration documentation. • Improve deployment, observability and operational reliability across AWS and

CI/CD. • Work with AI engineers on data ingestion, feedback capture, tracing, evaluation

support and cost and latency tracking. • Contribute to technical decisions, code review, testing and documentation,

ensuring important knowledge is shared across the team.

Core Requirements • 5+ years of backend or full-stack engineering experience, with strong production

Python experience. • Strong experience building APIs, preferably with FastAPI or similar Python

frameworks. • Solid database experience with PostgreSQL or similar relational databases,

including schema design, migrations, indexing, and query performance. • Experience with SQLAlchemy, Alembic, or comparable Python database tooling. • Experience designing systems for asynchronous or long-running work: queues,

workers, retries, batching, status tracking, or similar. • Good understanding of API security, authentication, and authorisation patterns

such as OAuth 2.0, JWTs, scopes, and service-to-service access. • Practical cloud experience, preferably AWS. • Comfortable working in a small team where requirements can be ambiguous,

collaborating on architecture while taking substantial responsibility for implementation and delivery.

• Strong attention to detail in naming, interfaces, documentation, tests, and operational behaviour.

If this role sounds like a strong fit, we would still encourage you to apply even if your experience does not line up perfectly with every point above.

Additional Experience • Experience with Terraform or other infrastructure-as-code tools, deployment

automation or zero-downtime deployment patterns. • Experience operating LLM- or ML-backed services in production, including

observability, tracing or experiment tracking. • Experience building multi-tenant, customer-scoped or externally integrated SaaS

platforms. • Experience with LTI 1.3, learning management system integrations or similar

interoperability standards. • Experience with data protection, GDPR or other regulated-data requirements. • Experience in EdTech, assessment technology or workflow-heavy B2B products. • Experience mentoring engineers or raising backend engineering standards within a

small team.

What Success Looks Like

Within the first few months, success would look like:

• backend and platform ownership, operational knowledge and implementation expertise being shared more broadly across the team;

• customer assessment workflows becoming more persistent, retryable and observable, with integrations that are easier to onboard, test and operate;

• AI assessment work having reliable backend support for data ingestion, feedback capture, tracing, evaluation and cost tracking.

Interview Process 1. 45-minute screening call with the Head of Engineering & AI, covering your

background, the role, and a short practical technical discussion. 2. 90-minute technical interview with the Head of Engineering & AI and the senior full-

stack architect. This will include Python/backend code review, API and database design discussion, and applied system-design questions around queues, reliability, security, observability, and operational trade-offs.

3. 45-minute call with the company founders, focused on the company, mission, team fit, and questions from both sides.

Benefits • Remote-first within the UK • Share options • Pension contributions matched by employer up to 5% of salary • Company laptop (MacBook Pro) • 25 days annual leave • Flexible working hours

• Learning budget for courses, books and tools • Conference attendance and speaking opportunities

Right to Work and Equal Opportunities

We are unable to sponsor visas for this role, so candidates must already have the right to work in the UK. sAInaptic is committed to equality, diversity and inclusion and welcomes applications from all suitably qualified candidates.

Specter

Senior Backend Engineer Full-time Hybrid London, UK, Remote (UK),

Remote (Europe - excluding France and Nordics) £100K - £160K

£100,000 - £160,000 base salary + annual performance bonus (£30-40K+) + ESOP after 6-9 months

About this role

We are looking for a Senior Backend Engineer with 5-15 years of experience to join Specter's engineering team and build the production infrastructure powering our agentic AI capabilities. You'll be a strong individual contributor who loves shipping real features used by real people, in this case, 300+ leading VC and PE firms discovering insights in private markets. We need someone who is killer in Python, has deep experience building and deploying APIs at scale, and is excited about leveraging AI in their work. This is a rare opportunity to join a small, fast-moving team at an inflection point where your backend expertise will directly shape the next generation of AI- powered investment tools. What will you be doing?

Building and shipping production-grade backend services and APIs using Python and FastAPI that power Specter's AI features

Developing the infrastructure and orchestration layer for agentic AI capabilities within the product

Working closely with databases (Postgres, ClickHouse) to enable intelligent data retrieval and AI-driven analysis

Mentoring teammates and contributing to engineering best practices as the team scales from ~7 to 30+ people

5 - 15 years of experience

Backend engineering experience with Python in production environments

Salary

£100K - £160K (£100,000 - £160,000 base salary + annual performance bonus (£30-40K+) + ESOP after 6-9 months)

Currency

Pound Sterling

Equity

Competitive equity

Visa Sponsorship Details

Open to visa transfers (e.g. OPT, H1B transfers) Open to visa sponsorships (e.g. new H1B, TN)

Hybrid work policy

5 days in-office in London (if London-based); remote across UK/Europe for non-London candidates

Full-time position

Location

London, UK, Remote (UK), Remote (Europe - excluding France and Nordics)

Report to

https://www.linkedin.com/in/dominikvacikar/

Tech stack

Python, FastAPI, PostgreSQL, ClickHouse, SQL, LLMs (OpenAI, Anthropic), Embeddings / Vector DBs, AI coding tools (Cursor, Claude)

About Specter

Specter delivers real-time data and insights on private companies, enabling investors to make informed, confident decisions. Harness the power of live data and AI-driven analysis to outsmart the competition

and make confident decisions in private markets.

Team size

30 employees

Website

www.tryspecter.com

LinkedIn

Visit

Total funding

$10M

Company locations

London

About the team

Specter is a tight-knit team of 6 people building the leading real-time data platform for private markets. The founders are deeply hands-on — you'll work directly alongside them daily on strategy, messaging, and execution. The team is highly technical and moves fast. Everyone wears multiple hats, and there's zero bureaucracy between you and impact. The current GTM team already includes a founding SDR who's proven the outbound playbook works — this hire will build on that momentum. Culture-wise, Specter values hustle, curiosity, and tech-savviness. They're looking for people who understand how startups work, can operate autonomously, and bring a bias for action every day. This isn't a corporate environment — it's an early-stage, profitable company where your contribution is visible and your growth trajectory is real.

Tech stack

Python, FastAPI, PostgreSQL, ClickHouse, SQL, LLMs (OpenAI, Anthropic), Embeddings / Vector DBs, AI coding tools (Cursor, Claude)

The product

Specter is a real-time data and intelligence platform for private markets. It provides investors — including venture capital firms, private equity funds, and corporate innovation teams — with live data and AI-driven analysis on private companies to help them source, evaluate, and win deals faster than the competition. The platform includes what the team describes as the biggest, most up-to-date

people database on the market, aggregating data from multiple major providers to deliver comprehensive company and talent intelligence. Specter enables its 300+ investment firm clients to: Track private companies in real time with live data feeds Leverage AI-driven analysis for competitive intelligence and deal sourcing Access quantitative and alternative data to inform investment decisions Contextualize companies by stage, sector, and growth signals — distinguishing early- stage startups from corporates Specter serves buyers across the private markets ecosystem — from VC partners and PE investors to fund analysts and M&A teams — helping them make informed, confident decisions and ultimately win the deals that matter most.

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Artifact AI

Staff Product Engineer

Full-time On-site or Remote

London, UK (preferred) New York City, NY Remote (UK) Remote (US)

$150K - $250K

About this role

We are seeking a Staff Product Engineer to join Artifact at a pivotal moment – as we

scale our AI-native platform across some of the world's largest accounting firms. You

will sit at the intersection of complex financial data, a gentic AI, and the enterprise-

grade systems that the accounting industry has relied on for decades. This is not a role

for someone who wants to specialise narrowly. You will own meani ngful surface area

end-to-end, from database schemas to the front-end component a client clicks on a

Tuesday, moving into the AI layer, the infra, or wherever the problem actually lives.

The accounting domain has resisted automation for 500 years because of its

complexity, its fragmentation, and the rigour it demands. Xero and Intuit have barely

moved the needle. We are building something more ambitious – agentic workflows

that sit on top of ERP systems like Workday and SAP, automate the high-volume, low-

value work that consumes accountants' time, and give firms the capacity to take on

more clients and do more meaningful work for the ones they have. The engineers who

thrive here understand that domain depth and technical craft are not separate things –

they are the same thing applied at different levels of the stack.

Key Responsibilities

Own and ship product features end-to-end across the full stack – backend (Python,

async, distributed systems) as the home base, with movement into AI, front end, and

infra as the work demands

Design and build reliable, high-quality systems with a strong emphasis on system

design and production-grade engineering

Integrate with and build on top of complex ERP and HCM systems (Workday, SAP,

and similar) and financial data pipelines

Develop configurable data extraction and ingestion workflows to handle the diverse

and often non-standard data formats that come with enterprise accounting

environments

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Build and iterate on AI-powered agentic workflows in close collaboration with AI

engineers, contributing to the intelligence layer when the problem calls for it

Leverage AI tooling aggressively to multiply your output – and know when to put

the tools down and get your hands dirty so the quality bar holds

Push back when direction is wrong, raise the bar of the people around you, and take

real ownership over what you build

5 - 10 years of experience

as a full-stack software engineer building complex products

Salary

$150K - $250K

Equity

Competitive

Visa sponsorship not available

On-site or Remote work policy

Hybrid in London (preferred; flexible on days per week) but remote in UK or US acceptable (strong preference for Eastern Time if in the US)

Full-time position

Location

London, UK (preferred), New York City, NY, Remote (UK), Remote (US)

Report to

https://www.linkedin.com/in/ahmedsalhin/

Tech stack

Python

About Artifact AI

Artifact is rebuilding accounting from the ground up. Not incrementally improving the

software – rebuilding the work itself, so one accountant can do what a team used to do

and a set of books closes itself in the background while a human stays in the loop.

Two products do the heavy lifting. Arti handles the core accounting workflow –

ingestion, matching, reconciliation, and journal posting. Omni sits on top of 600+

platforms and lets accounting firms build agentic workflows in natural language,

capturing their expertise and operationalising it at scale. Together they are not a

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productivity tool – they are a new layer of infrastructure for how accounting work

actually gets done.

The firms using Artifact today are not experimenting. They are running their clients'

month-end on it. Backed by a16z and based in London and New York, Artifact is at the

point where the technology is proven, the clients are real, and growth is about to bend

sharply. The people joining now will shape what that looks like.

Team size

20 employees

Founded

2025

Website

getartifact.com

LinkedIn

Visit

Total funding

$4.5M

Company locations

London, UK +3

Tech stack

Python

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