Staff Engineer • Paris - CDI

Company

• Jus Mundi is a Paris-based legaltech founded in 2019 with one mission: power global justice, by making international law and arbitration genuinely accessible through data and AI.

• The platform centralises the most comprehensive collection of arbitration material in the world: awards, treaties, case law, institutional rules and publications, largely multilingual and until now scattered or locked away.

• Around 100 people, 39 nationalities, and customers in more than 100 countries. Offices in Paris, New York, London, Singapore and Mexico City.

• 8 figures ARR, 35 percent of it from the US, with growth targeted at 70 to 75 percent per year.

• A 22M$ Series B closed in late 2024, led by Acton Capital and True Global Ventures with C4 Ventures and FJ Labs following, one of the largest rounds raised by a European legaltech.

• Exclusive data partnerships with more than 100 leading arbitration institutions, including a 2026 collaboration with the Court of Arbitration for Sport.

Products

• Jus Mundi: multilingual search across international law and arbitration, so a lawyer finds in minutes what used to take days of manual research.

• Jus AI: an agentic assistant built specifically for arbitration. Natural language questions with cited answers, document analysis, summarisation, translation, cross-jurisdiction comparison, and agents that take over repetitive work.

• Jus Connect: the network and data layer. Identify arbitrators, counsel and experts, map who worked on which case, check conflicts of interest, build shortlists.

• The product is opening up beyond its own interface: in March 2026 Jus Mundi and Legora announced the first agent-to-agent integration in arbitration, rolling out through 2026.

• Next horizon: agentic systems that reason over private client data and connect to internal databases, the web and partner sources.

Why now

• The company is deliberately simplifying. An early microservices architecture that was never justified by traffic volume is being brought back toward a pragmatic, more monolithic design.

• Data volume is about to change scale: from roughly 100k documents today to several hundred million over time. The engineering decisions taken this year will be lived with for years.

• A new CTO joins in September 2026, with the founding CTO staying involved through the transition. The technical standards of the next phase are still being written.

• Engineering has grown to around 25 people across 5 squads with no dedicated technical reference above squad level. This role is created to close that gap.

• AI-assisted development is being rebuilt into the way the whole team works, and this role helps set that standard rather than inherit it.

• For a staff engineer, that combination is rare: a full transformation to run end to end, with real headroom for a bigger role afterwards.

The role

• You join the Platform team, the only fully transverse squad, and act as a technical force multiplier across every product and engineering squad.

• The north star is zero-friction delivery: shipping business value fast and securely, through simple and standardised engineering practices.

• Your first mandate is the new engineering framework: the standards for reliability, security, testing and deployment that every squad will work to.

• This is an individual contributor role with no direct reports, positioned at level 4 to 5 on the six-level engineering ladder: autonomous, and making others autonomous.

• Half the value of the role is influence. You become the reference developers come to, and the working example of the product-minded engineer Jus Mundi wants across its teams.

• You report to Yohan Daddou, Head of Infrastructure, who is also the hiring manager for the role.

What you'll do

• Define and roll out the engineering framework across squads: reliability, security, testing, deployment.

• Build a testing environment developers actually trust, and keep it alive instead of letting it decay.

• Drive the architectural transition away from immature microservices, deciding service by service what gets reintegrated and how.

• Work inside the product squads on their developer experience: tooling, CI/CD, feedback loops, everything that quietly slows a developer down.

• Call out tech for tech's sake. When a squad over-engineers, bring it back to the simplest solution that serves the customer.

• Coach engineers toward a product builder mindset, mostly by example and in the flow of their work rather than through formal training.

• Take on the critical stack work nobody has time for: PHP and Symfony upgrades, third-party library migrations, infrastructure hardening.

• Step into critical incidents and drive them to resolution.

• Write production code across several domains, switching context between technical subjects without losing depth.

Ways of working

• An EPD organisation (engineering, product, design) built on autonomous squads, with product and tech alignment treated as a first-class concern.

• AI-assisted development is not optional here: agentic coding tools are expected in daily practice and the team is actively rethinking its methods around them.

• A six-level engineering ladder is being rolled out, with explicit expectations at each level.

• Pragmatism over purity. The past years of tech for tech's sake are openly acknowledged, and the current direction is simplicity, reuse and reintegration.

• High technical standards, a fast-moving environment, and communication treated as an engineering skill rather than a soft one.

Team

• Around 25 engineers in 5 squads: Platform (infrastructure, security, developer tooling), Legal Data Collection, Search, Core AI, and User Lifecycle and Growth.

• Platform is 3 engineers plus an engineering manager. It is your home squad, not your scope: most of your time is spent in the other squads.

• Day-to-day collaborators: Yohan Daddou (Head of Infrastructure), Mathieu Caudron (Tech Lead Manager), the squad EMs and PMs, the Core AI team, and security stakeholders.

• Leadership: Jean-Rémi de Maistre (co-founder and CEO), Thomas Latterner (co-founder and CTO), Ayushman Dash (Head of AI), Stéphane Altounian (VP of Product).

• 39 nationalities, and a team that is international by default rather than by policy.

Stack

• Backend: PHP, Symfony

• Also in production: Node.js, Nuxt

• Architecture: microservices being reintegrated toward a pragmatic monolith

• Infrastructure: Kubernetes, infrastructure as code, CI/CD, observability

• AI: in-house AI layer powering Jus AI, agentic reasoning over the arbitration corpus

• Data: large-scale multilingual legal document processing and search

• Tooling: agentic coding assistants (Cursor, Claude Code and similar) in daily use

• PHP is the core stack but not a gate: the team hires on engineering maturity and assumes a strong engineer picks up a new language.

At a glance

• Compensation: 80-110k€ + equity

• Location: Paris 8e, avenue Hoche

• Remote: 3 days/week, 8 weeks intl. flex

• Contract: Full-time, permanent

• Reporting to: CTO