Senior Backend Engineer — Data Platform & AI Agents

Jus Mundi; Paris; Hybride; EUR 90 000 - 130 000; Plein temps

Avantages offerts par ce poste

Hybrid work (2 days on-site)

5 weeks vacation

Private health insurance (family)

Restaurant vouchers (60%)

JM Fest company-wide events

ClassPass wellness support

Relocation assistance to France

Résumé du poste

Jus Mundi is building a Data Platform to turn a vast multilingual corpus of legal documents into trusted, searchable data. We are hiring a Senior Backend Engineer with hands-on AI experience to own the platform services, agents, catalog, and processing layers.

You will work with LLMs and agent orchestration in a high-ownership role, shaping architecture and contributing to a scalable, end-to-end system. You will join the Data team within EPD and collaborate with Legal Content, Search, AI, and

Qualifications

• 5+ years shipping and operating production backend or data services.
• Hands-on experience building agent orchestration in production with tool calling, memory and state management.
• Strong PostgreSQL data modelling and schema design for evolving data.
• Experience with containers, CI/CD, and Kubernetes.
• Fluent English in speaking and writing.

Responsabilités

• Build agents that acquire documents from hundreds of sources and manage orchestration loop and memory.
• Own transactional catalog and API fronting the platform’s data; design robust schemas with provenance and versioning.
• Process documents with OCR and metadata extraction; ensure derived data is versioned and regenerable.
• Implement quality measures with tests, thresholds, and regression tracking; support human-in-the-loop architectures.
• Deploy, monitor, and operate services; provide observability with logs and traces across document history.
• Collaborate with Search, AI and Product squads to define stable interfaces and RFCs.

Connaissances

Backend engineering

Python

Async I/O

API design

Agent orchestration

LLM systems

Multilingual data processing

English fluency

Outils

Postgres

Kubernetes

LangChain

LangGraph

LlamaIndex

Description du poste

Join Jus Mundi – To Power Global Justice

Founded in 2019 and recognized as a mission-led company, Jus Mundi is pioneering legal technology to power global justice through artificial intelligence.

Headquartered in Paris, with additional offices in New York, London, and Singapore, Jus Mundi serves over 150,000 users, including top law firms, multinational corporations, government bodies, and academic institutions in more than 90 countries. By combining legal expertise with cutting-edge AI technology, we provide global legal intelligence, data-driven arbitration professional selection, and business development services.

What Makes Jus Mundi the Place to Be

• Our Values: With core values as Listen (Solve for the Legal Community), Iterate (Start Sharp, Stop Smart), Commit (Step In, Own the Outcome), Belong (Build together through diversity), Uphold (Aim for Justice with Integrity), we cultivate a dynamic environment that encourages collaboration, innovation, and continuous growth.
• Legal Is the Next Frontier for GenAI: Legal is one of the top industries ready to be transformed by GenAI. At Jus Mundi, we’re building transformative AI where it has the power to make the most impact.
• Proven Product Market Fit: Jus Mundi has secured product-market fit in global markets since launch, partnering with top-tier law firms, government bodies, and major corporations, including: Freshfields, Quinn Emanuel, Wong Partnership, Total Energies, Canada, UK, and Japan.
• Strategic Investment: In 2024, we raised over $20 million in Series B funding from prominent strategic international investors, including Acton Capital, True Global Ventures, C4 Ventures, and FJ Labs, fueling our growth and innovation.
• Legal Meets Tech: Our engineers and former lawyers collaborate closely with large language models (LLMs) to pioneer the future of generative AI and reshape professional services.
• Exceptional Team: Work with talented professionals from industry leaders, including engineers, legal experts, and AI specialists from companies like Google and Amazon who are pushing the boundaries of legal tech.

About the Role

Jus Mundi is building the AI layer for international law and arbitration — turning a vast, multilingual corpus of case law, treaties, and legal analysis into answers practitioners can trust. We are now expanding beyond arbitration into new legal verticals, and each one potentially adds millions of documents to that corpus.

To support that, we are building a new Data Platform: an autonomous, agent-driven system that discovers, acquires, processes and enriches legal documents end to end, and becomes the company-wide source of truth that Search, AI and Product all consume. It replaces our legacy ingestion paths rather than patching them.

We are looking for a Senior Backend Engineer with hands-on AI experience to build it with us. You will own the services behind the platform: the agents that acquire documents from hundreds of heterogeneous sources, the transactional catalog and API that everything reads from, and the processing layer that turns raw files into searchable, well-described documents.

This is a hands-on senior role with high ownership and real architectural latitude. Backend depth is the core of the role; you should be comfortable working with LLMs and agent orchestration as a first-class part of the system, but this is not a modelling or research position.

The Team

You will join the Data team within EPD (Engineering, Product and Design) — a small, senior team made up of an Engineering Manager, a backend/full-stack engineer, and an AI engineer reinforcing us over the coming months.

We work in close collaboration with the Legal Content team, who own what “correct” means for a legal document, and with the Search, AI and Product squads who consume what the platform produces.

Your mission at Jus Mundi

• Agentic ingestion (core of this role): Build the agents that acquire documents from hundreds of heterogeneous sources — the orchestration loop, tool calling, memory, and the guarantees that make a sweep provably complete rather than approximately complete.
• Backend services and data model (core of this role): Own the transactional catalog and the API in front of it — the single door to the platform’s data. Design a schema that holds heterogeneous, evolving legal documents with provenance and confidence on every field, and that absorbs new contributors without a migration.
• Document processing: Extraction, OCR and metadata over a messy multilingual corpus. Derived data stays versioned and regenerable, so a better model means a re-run rather than a re-acquisition.
• Quality without manual gates: We deliberately have no human approval step before a document becomes searchable, so quality has to be measured. Test sets, thresholds, confidence and regression tracking are how a component earns its way into production. We will develop Human-In-the-Loop architecture
• Run what you build: Deploy, instrument and operate your own services. Metrics, logs and traces that let anyone reconstruct a single document’s whole history from one identifier.
• Leverage across squads: Search, AI and Product all build on this platform. You design the stable interfaces they consume, write the RFCs that get decisions validated, and help us grow the team.

Scope will move as the platform does — this is an early-stage system, and we would rather you help shape the roadmap than inherit it.

Preferred Experience And Skills

• Backend Engineering Depth (critical requirement): 5+ years shipping and operating production backend or data services, with strong Python . Async I/O, API design, testing discipline, and a track record of owning services in production rather than handing them over.
• Agentic & LLM Systems (critical requirement): Hands-on experience building agent orchestration in production — tool/function calling, memory and state management, error recovery, bounded context, and deterministic contracts wrapped around a non-deterministic core. Custom architecture or a framework (LangGraph, LangChain, LlamaIndex, or similar) are equally welcome; what matters is that you can point at something you shipped and had to keep working.
• Data Modelling: Postgres in depth — schema design for heterogeneous and evolving data, jsonb versus typed columns, indexing, full-text search, migrations under load, and a real feel for transactional correctness.
• Systems Judgment: Queues or streams, idempotency, at-least-once semantics, atomic writes, object storage treated as immutable truth. You design for retry, reproducibility and graceful degradation rather than assuming the happy path.
• Document & Data Processing: PDF and HTML text extraction, OCR, and structured metadata extraction with LLMs — plus realistic judgement about where quality breaks and what that costs downstream. Multilingual corpora a strong plus.
• Ownership & DevOps Mentality: Containers, CI/CD, Kubernetes or equivalent. You build it, you run it, you own it — including when it pages.
• Senior Behaviours: Turns ambiguity into a plan and a document others can act on; makes explicit trade-offs rather than reaching for the perfect solution; mentors peers; takes accountability for outcomes. Fluent English (our working language, oral and written).

Nice to Have

• Web crawling and scraping at scale — pagination traps, rendering, rate limits, source drift, dedup. We are taking an agentic-first approach, so this is a real bonus rather than a requirement.
• Legal tech, or another domain where being confidently wrong is expensive.
• Search infrastructure (Elasticsearch / OpenSearch) and multilingual retrieval.
• Enough TypeScript/JS to contribute to our internal back-office UI.
• Experience with the MCP ecosystem, or agent tooling you built yourself.
• Open-source contributions, or a portfolio of systems you can talk through in depth

Interview process

• Introductory Video Call with Laurine, Talent Manager (30 min)
• Technical Test at home (1-2 hours) and Remote Debrief Test Session (45 min)
• Live Programming Exercice (1h30)
• Product Interview with an Engineering Manager and a Product manager (45 min)
• Meet the team at the Office + Lunch or Afterwork
  • Immersion with teams (1h30)
  • Culture & Values Interview (45 min)
• Last call with Jean-Rémi, CEO, or Anna, VP of People (30 min)

Please note that, due to the nature of the sector we operate in, the final steps of our recruitment process include reference calls and a background check.

Need More Reasons to Join Us?

• Enjoy a hybrid working organization that combines remote and on-site work (2 days).
• Get 5 weeks of vacation each year, and take them whenever it suits you.
• Receive 100% coverage of private health insurance for yourself and your children.
• Enjoy 60% company-funded restaurant vouchers for your weekday meals (Swile).
• Participate in company-wide summits called JM Fest to connect and inspire.
• Stay active with a co-financed ClassPass membership by accessing a variety of fitness and wellness activities.
• Enjoy the flexibility to work from anywhere across the globe for up to 8 weeks per year.
• Receive relocation assistance to help ease your transition to France.
• Last but not least: Experience a commitment to building a warm, inclusive, and diverse environment.

At Jus Mundi, we believe that diversity, equity, and inclusion are key to our success. Confidence can sometimes hold us back from applying for a job, but we’ll let you in on a secret: there’s no such thing as a ‘perfect’ candidate. We celebrate diverse backgrounds, experiences, and identities, and we encourage you to apply regardless of how you identify. Whether you’re early in your career or a seasoned professional, your unique perspective and skills are what matter most. Join us in building a workplace where everyone feels valued, empowered, and excited to contribute their best work every day.