2,122,757open jobs
134,382companies
240,476added this week
Browse all
Location
In office (London)
Seniority
Principal · 10+ years exp
Visa
Licensed UK visa sponsor

Confirmed on the employer's own hiring board on Nov 6, 2026. First seen by Alion on Nov 5, 2026. Scale AI scores B on the Alion truth index.

Overview
Company
Impact
Profile match
Scale AI is an American company founded in San Francisco in 2016 that supplies the training data, evaluation and tooling behind large artificial intelligence systems. It began with human-labelled annotation for autonomous driving and computer vision, then expanded into reinforcement learning from human feedback, expert data generation, model evaluation and full-stack deployment platforms for enterprises and governments. In 2025 Meta acquired a large minority stake and hired co-founder Alexandr Wang, after which the company continued under new leadership serving defence, public sector and commercial customers.

Principal Software Engineer, Global Public Sector 

Scale’s rapidly growing Global Public Sector team is focused on using AI to address critical challenges facing the public sector around the world. Our core work consists of:

  • Creating custom AI applications that will impact millions of citizens
  • Generating high-quality training data for national LLMs
  • Upskilling and advisory services to spread the impact of AI

We are hiring a Principal Engineer to join a small team of our most senior engineers who take on the problems no one else can. You will work at the earliest stage of our engagements: shaping the technical approach with clients, defining the technology we build on, and turning ideas into working prototypes fast. You will step in when a project is stuck or a problem is unusually hard, and turn what you learn in the field into shared capabilities every team can build on.

This is a very senior, hands-on role. Our engineering organisation is young, so mentoring is a core part of the job: you will raise the bar for how we design, build and deliver, and grow the next generation of technical leaders around you. The role is based in London.

At Scale, we’re not just building AI solutions, we are building repeatable blocks to enable the public sector to transform their operations and better serve citizens through cutting-edge technology. If you’re ready to shape the future of AI in the public sector and be a member of our rapidly expanding team, we’d love to hear from you.

You will:

  • Take on the hardest technical problems across our programs, stepping in where projects are stuck or the path forward is unclear
  • Lead the technical side of early engagements: work with clients to scope problems, shape proofs of concept and keep the scope needed to prove value as small as possible
  • Build working prototypes quickly, from AI agents and evaluation pipelines to data and knowledge systems, and take the most promising ones to production
  • Define the technology and architecture our solutions are built on, keeping them cohesive, secure and reusable across clients
  • Mentor engineers across a young organisation through pairing, design and code reviews, and set the bar for engineering excellence
  • Partner with Directors, VPs and client executives to navigate high-stakes business and technical trade-offs, including travel to client sites as engagements require
  • Turn patterns from the field into reusable capabilities, contributing components back to our core platform so every engagement starts further ahead
  • Lead from the front on agentic engineering, both in the AI systems we build and in how our teams use coding agents day to day, and push the boundaries of what’s possible with AI

Ideally you’d have:

  • A strong engineering background, with a Bachelor’s degree in Computer Science, Mathematics or a related quantitative field (or equivalent practical experience)
  • 10+ years of post-graduation engineering experience, with demonstrated proficiency in languages such as Python, TypeScript/JavaScript, Java, or C++
  • 5+ years of experience applying AI/ML in production environments, such as building generative/agentic AI applications, RAG systems or evaluation pipelines
  • Strong problem-solving skills, with a track record of taking ambiguous, early-stage problems from a blank page to a working prototype and into production
  • Deep expertise in system design and architecture, including experience with cloud-based machine learning tools and platforms (e.g. AWS, GCP, Azure)
  • Experience mentoring engineers and raising the technical bar of a team or organisation
  • Comfort working directly with clients, from their engineering teams to senior executives
  • Excellent written and verbal communication skills to collaborate effectively in a cross-functional environment

Nice to haves:

  • Past experience in a forward deployed engineering role
  • Experience working at a startup, particularly as a founding engineer
  • Experience building and deploying large-scale AI solutions
  • Experience delivering technology programs for governments or regulated industries
  • Experience deploying solutions on-prem or in customer-controlled environments
  • Current or previous UK government security clearance (e.g. SC or DV)

PLEASE NOTE: Our policy requires a 90-day waiting period before reconsidering candidates for the same role. This allows us to ensure a fair and thorough evaluation of all applicants.

About Us:

At Scale, our mission is to develop reliable AI systems for the world’s most important decisions. Our products provide the high-quality data and full-stack technologies that power the world’s leading models, and help enterprises and governments build, deploy, and oversee AI applications that deliver real impact. We work closely with industry leaders like Meta, Ernst & Young, Mayo Clinic, Time Inc., the Government of Qatar, and U.S. government agencies including the Army and Air Force. We are expanding our team to accelerate the development of AI applications.

We believe that everyone should be able to bring their whole selves to work, which is why we are proud to be an inclusive and equal opportunity workplace. We are committed to equal employment opportunity regardless of race, color, ancestry, religion, sex, national origin, sexual orientation, age, citizenship, marital status, disability status, gender identity or Veteran status. 

We are committed to working with and providing reasonable accommodations to applicants with physical and mental disabilities. If you need assistance and/or a reasonable accommodation in the application or recruiting process due to a disability, please contact us at [email protected]. Please see the United States Department of Labor's Know Your Rights poster for additional information.

We comply with the United States Department of Labor's Pay Transparency provision. 

PLEASE NOTE: We collect, retain and use personal data for our professional business purposes, including notifying you of job opportunities that may be of interest and sharing with our affiliates. We limit the personal data we collect to that which we believe is appropriate and necessary to manage applicants’ needs, provide our services, and comply with applicable laws. Any information we collect in connection with your application will be treated in accordance with our internal policies and programs designed to protect personal data. Please see our privacy policy for additional information.

PLEASE NOTE: Our policy requires a 90-day waiting period before reconsidering candidates for the same role. This allows us to ensure a fair and thorough evaluation of all applicants.

About Us:

At Scale, our mission is to develop reliable AI systems for the world's most important decisions. Our products provide the high-quality data and full-stack technologies that power the world's leading models, and help enterprises and governments build, deploy, and oversee AI applications that deliver real impact. We work closely with industry leaders like Meta, Ernst & Young, Mayo Clinic, Time Inc., the Government of Qatar, and U.S. government agencies including the Army and Air Force. We are expanding our team to accelerate the development of AI applications.

We believe that everyone should be able to bring their whole selves to work, which is why we are proud to be an inclusive and equal opportunity workplace. We are committed to equal employment opportunity regardless of race, color, ancestry, religion, sex, national origin, sexual orientation, age, citizenship, marital status, disability status, gender identity or Veteran status. 

We are committed to working with and providing reasonable accommodations to applicants with physical and mental disabilities. If you need assistance and/or a reasonable accommodation in the application or recruiting process due to a disability, please contact us at [email protected]. Please see the United States Department of Labor's Know Your Rights poster for additional information.

We comply with the United States Department of Labor's Pay Transparency provision. 

PLEASE NOTE: We collect, retain and use personal data for our professional business purposes, including notifying you of job opportunities that may be of interest and sharing with our affiliates. We limit the personal data we collect to that which we believe is appropriate and necessary to manage applicants’ needs, provide our services, and comply with applicable laws. Any information we collect in connection with your application will be treated in accordance with our internal policies and programs designed to protect personal data. Please see our privacy policy for additional information.

Free account
Stop reading job ads. Get the ones that fit.
One free account turns this page into a shortlist built around your stack, your level and your pay.
Match on every job. Stack, seniority, pay and location, scored against your profile.
2,122,757 open roles. Read straight off company career pages, refreshed every day.
Unlimited applications. Every one you send is tracked in one place, on-site or on a company board.
3 tailored CVs a month. Rewritten for the exact job you are applying to. Included free.
Create a free account Continue with Google
Free forever. No card. Under a minute.

Your match

How well do you fit this role?
Two answers are enough for a real match. No account needed.
Check my fit
Answers stay in this browser until you create an account.

Recommended for you based on this role

Backend
Similar stack
Same company
London
In office · London
Python
Java
Python
Django
Databases
MySQL
AI/ML
Machine Learning
DevOps
CI/CD
Management
Agile
Apply
.NET Developer 2 hours ago
Hybrid · Full-Time · Leicester
C#
C#
.NET
DevOps
Rest API
Azure
CI/CD
Git
Management
Agile
Apply
In office · London
Java
Java
Spring Boot
Databases
Cassandra
AI/ML
Machine Learning
Mobile
Reactive Programming
DevOps
CI/CD
Management
Agile
Apply
In office · 8+ years exp · Glasgow
JavaScript
Java
Java
Spring Boot
Databases
Cassandra
Apache Kafka
Frontend
React.js
DevOps
CI/CD
AWS
Management
Agile
Apply
In office · Glasgow
Python
Java
Java
Spring Boot
AI/ML
AI Agents
DevOps
Terraform
AWS
Apply
up to $58k per year · Hybrid · London
Web3
Pimlico
Apply
Technical Analyst 1 day ago
up to $81k per year · Hybrid · London
Python
SQL
Databases
Snowflake
Web3
Pimlico
Apply
$84k – $115k per year · Hybrid · Bracknell · London
Python
SQL
Databases
Snowflake
AI/ML
Vertex AI
Machine Learning
DevOps
GCP
Git
GitLab
Management
Agile
Apply
In office · Contractor · London
JavaScript
Frontend
React.js
Mobile
React Native
TestFlight
DevOps
CI/CD
Management
Agile
Scrum
Kanban
Apply
Data Analyst 1 day ago
Hybrid · Full-Time · London
Python
SQL
Analytics
Tableau
Power BI
Looker
Apply
See all jobs
This is one of many
2,122,757 more open roles from verified company boards, updated every day.