---
title: 'Full-Stack Engineer at HASH'
canonical: 'https://feeny.ai/job/full-stack-engineer-hash-london-e3e5zj0y8ysk'
type: 'job'
last_seen: '2026-09-05'
---

# Full-Stack Engineer at HASH

- **Company:** HASH
- **Location:** London, United Kingdom
- **Employment:** full-time
- **Work type:** onsite
- **Posted:** 2026-01-28
- **Last confirmed live:** 2026-09-05
- **Apply:** https://jobs.gem.com/hash/am9icG9zdDqm5GdqYOZP6pdaTatZIwd-

## Job description

## About HASH

HASH's open-source platform helps firms integrate both structured and unstructured information into knowledge graphs that support simulating, optimizing and automating processes. Our [mission](https://hash.ai/about/mission) is to solve information failure, and help everybody make the right decisions. To that end, we're unapologetically excited. Actions speak louder than words, and we measure performance by output. We prioritize speed, and measure product delivery timelines in hours and days, not months and years. We value high-energy, high-expectations people who do what they say and say what they mean. We're committed to building a high-commitment, high-trust environment, and believe that the best teams are most productive together, in-person. We're therefore currently hiring exclusively in both London (UK) and Berlin (Germany) to join the firm.

## About the role

Full-stack engineers implement the majority of HASH's user-facing features. They write code on the frontend and backend, unblocking themselves, and ensuring HASH responds to user needs and ships new functionality fast. We are hiring new engineers based in London, UK as well as Berlin, Germany to join our team in-person.

## Requirements

- You must possess expert-level proficiency in TypeScript and React. Additional experience with Rust is nice-to-have but not required.
- Experience working with Effect and HTML Canvas, as well as frontend graphics and animation libraries are also beneficial, as is familiarity using and customizing component libraries such as Material UI, Base UI or Ariakit, and working with type-safe styling systems like Panda.
- You should be interested in not only moving fast, but also in building performant solutions.
- In this full-stack role, you should be as comfortable optimizing data structures and storage systems as you are in pushing front-end web frameworks to their limits. If you are more interested in frontend engineering only, see our separate FE Engineer opening(s).

## What you'll work on

- You'll work on both the frontend and backend of new features at HASH, touching most parts of the HASH codebase.
- The vast majority of your work will be open-source, and many of the components you build should be designed modularly, supporting their use in third-applications, as well.
- You'll collaborate directly with experienced, organized, and technical UX/UI designers in addition to company leadership (both the CEO and CTO).

## Benefits

We offer leading equity-weighted total compensation, including competitive salaries and tax-advantaged options. We also offer:

- Employer pension contributions
- At least 30 days holiday annually
- Quarterly in-person team retreats around the world

HASH's founders have previously founded and sold companies like Stack Overflow and Trello for hundreds of millions and billions of dollars.

This role pays £70,000-£120,000 base/bonus + meaningful equity.

## About HASH

## Company Overview
- **One-liner**: HASH is an open-source platform for decision-making that integrates live data, constructs ontologies, and creates shared understanding through collaborative agent-based simulation and knowledge modeling tools.
- **Entity Type**: Private (Seed stage)
- **Headquarters**: London, United Kingdom
- **Founded**: 2019
- **Founders**: Joel Spolsky and Jude Allred

## Core Business
- Primary industry/industries: Technology, Information and Internet; Business Decision-making Software; Simulation & Modeling
- Target customers: B2B, Enterprise (with a focus on safety-critical supply chain, biopharmaceutical logistics, and complex systems modeling)
- Mission or purpose statement: "Eliminate information failure and help everybody make the right decisions."

## Products & Services
- **[HASH Platform (hash.ai/hash.dev)]**: An open-source, collaborative workspace for structured knowledge that integrates live data, enables ontology construction, and provides fast, distributed agent-based simulation. Combines knowledge capture and modeling tools for complex systems decision-making.
- **Block Protocol (blockprotocol.org)**: An open standard they drive for interoperable, data-driven blocks, contributing to the commons.
- **Open Source Simulation Engine**: Built in Rust/WASM, focused on agent-based simulation and formal verification of distributed systems.

## Market Standing
- **Valuation/Market Cap**: Not disclosed
- **Key Metrics**: Annual Revenue of approximately $1 million; Total Funding of $2.5 million (1 seed round)
- **Notable Investors/Partners**: Zetta Venture Partners (Lead), Root Ventures, with 6 total investors in the seed round. They also work with the Advanced Research + Invention Agency (ARIA) and scientists from the University of Oxford.
- **Growth Signals**: Headcount grew 14.3% YoY (now 9 employees); actively recruiting for new engineering and research roles; conducting high-profile research programs with ARIA and Oxford on safety-critical supply chains; 2,460 LinkedIn followers with 15.6% yearly growth; employer rating of 5.0/5.0 on Wellfound.

## Competitive Advantages
- **Unique Open-Source Approach**: All core tools are open source, building trust and allowing external validation—rare in the decision-modeling space.
- **Technical Moat**: Combines graph-backed world models, formal verification, and agent-based simulation (Rust/WASM) with AI research. Very few companies operate at this specific intersection.
- **High-Impact Focus**: Working on genuinely hard problems (eliminating information failure) with safety-critical applications (supply chains, biopharma logistics), giving them a defensible niche.
- **Elite Talent Sourcing**: Proactively identify and hire exceptional people through their own tooling and community, not just open applications.

## Strategic Focus
- Current priorities: Building a next-generation platform for decision-making via graph-backed world models and AI; expanding into safety-critical supply chain management with government and research partners; advancing their open standard (Block Protocol).
- Direction for growth: Scaling the engineering team (Rust, TypeScript, Python), deepening AI research (graph learning, formal verification), and expanding use cases in complex systems simulation.

## Why Work Here
- **Culture & Work Style**: "We care about output, ownership, and quality." They value raw intelligence, high-energy, and standout performance. The team works in public, contributing heavily to open source.
- **In-Person Focus**: Operates in-person from offices in **London** (HQ) and **Berlin**, with company-wide get-togethers at least twice a year in Europe. Some remote flexibility is available (e.g., Full-Stack Engineer roles can be in-office or remote).
- **Compensation & Perks**: "Leading compensation" with meaningful equity, competitive salaries, an 'unlimited' equipment and learning allowance, and at least 30 days paid time-off each year.
- **Engineering Culture**: Work on hard problems in Rust, TypeScript, and Python, including formal verification, graph learning, and simulation. They emphasize a fast, conviction-based hiring process with decisions made "within days, not weeks."
- **Hiring Process**: A short introductory call followed by a focused work sample or technical deep-dive. Most hires begin with HASH reaching out, but candidates can apply for specific roles.

## Sources
1. [hash.ai](https://hash.ai/careers)
2. [hash.dev](https://hash.dev/careers)
3. [linkedin.com](https://linkedin.com/company/hashintel)
4. [builtin.com](https://builtin.com/company/hash)
5. [jobs.gem.com](https://jobs.gem.com/hash)
6. [blockprotocol.org](https://blockprotocol.org)

## Other roles at HASH

- [Technical Lead](https://feeny.ai/job/technical-lead-hash-london-w4hvjac5jhmm) — London, United Kingdom
- [Product Designer (UX/UI)](https://feeny.ai/job/product-designer-ux-ui-hash-london-j5ms9egvkbjh) — London, United Kingdom
- [Integrations Engineer](https://feeny.ai/job/integrations-engineer-hash-london-mt5wag63x2eb) — London, United Kingdom
- [Forward-Deployed Engineer](https://feeny.ai/job/forward-deployed-engineer-hash-london-b7q0bwqwmrqq) — London, United Kingdom
- [Design Engineer](https://feeny.ai/job/design-engineer-hash-london-gcmsp6c4ndwq) — London, United Kingdom
- [Brand Designer](https://feeny.ai/job/brand-designer-hash-london-1wytwyqmnrpq) — London, United Kingdom
- [Marketing & Communications Lead](https://feeny.ai/job/marketing-communications-lead-hash-london-a2haat5mqgrw) — London, United Kingdom
- [Solutions Lead](https://feeny.ai/job/solutions-lead-hash-london-0tvys1wc1f5j) — London, United Kingdom
- [Outbound Business Development Lead](https://feeny.ai/job/outbound-business-development-lead-hash-london-xk00zm3t32kh) — London, United Kingdom
- [Enterprise Sales Lead](https://feeny.ai/job/enterprise-sales-lead-hash-london-4gzfmtxbxcc6) — London, United Kingdom