Research Engineer - Search and Services at Mistral (Paris, France)Research Engineer - Search and Services

Mistral provides full-stack AI solutions: from frontier models to developer tools, applications, and compute. We partner with enterprises tackling the hardest problems across high-stakes industries like finance, manufacturing, defense, healthcare, and the public sector, co-creating customized AI systems that they can run on their terms. We are a dynamic, collaborative team passionate about AI and its potential to transform society. Our diverse workforce thrives in competitive environments and is committed to driving innovation. Our teams are distributed between Europe, North America, Asia and the Middle East. We are creative, low-ego and team-spirited.

We are seeking a talented and experienced Research Engineer to join our newly forming Search and Services Platform team within Research Platform. You will build and operate the large-scale search and services that our models rely on as tools — from self-hosted, web-scale, search indexes to knowledge graphs and databases served through MCP. You will work closely with researchers and with the pretraining data, sandbox and data platform teams to make these services reliable, scalable and fast, on infrastructure measured in hundreds of terabytes of NVMe storage and thousands of CPU cores to support both data generation and critical training runs.

As a Research Engineer on the Search and Services team, your responsibilities will include (but may not be limited to):

• Designing, building and operating large-scale search infrastructure: self-hosted Vespa clusters indexing web-scale corpora, managed indexes for smaller corpora, and vendor search endpoints.
• Self-hosting and maintaining a wide range of structured data sources — knowledge graphs (Wikidata, UniProt, Materials Project), scholarly data (OpenAlex, OpenAIRE), statistical databases (Eurostat, World Bank, IMF, OECD), open data portals and more.
• Designing interfaces and tools to expose to the models and agents to use the services in different ways (direct YQL or SPARQL queries, or more refined and constrained MCPs to mimic external services) to support data generation and agentic training.
• Building the data pipelines that ingest, index and serve massive datasets, including indexing our own pretraining corpora for exploration, deduplication and eval-leakage checks.
• Building strong relationships with researchers and adjacent teams (pretraining data,, sandbox, data platform), understanding their workflows and enabling them to achieve more by leveraging your expertise.
• Communicating and producing documentation or any content that will help teams make the most of the services you'll build.

• 5+ years of successful experience in search engineering, data infrastructure, or a similar SRE / platform role.
• Proficiency in software development (Python, Go...) and programming best practices.
• Hands-on experience with large-scale search or data systems (e.g. Vespa, Elasticsearch / OpenSearch, ClickHouse or similar).
• Exposure to site reliability engineering: root cause analysis, in-production troubleshooting, on-call rotations...)
• Exposure to infrastructure management: containerization, orchestration (Kubernetes), infra-as-code, monitoring, logging, alerting, observability...).
• Experience designing and operating data pipelines that address large amounts of data.
• Excellent problem-solving and communication skills (ability to contextualizing, gauging risks and getting buy-in for high stakes and impactful solutions).
• Ownership, high agency and constantly seeking to learn and improving things for others.
• Autonomous, self-driven and able to work well in a fast-paced startup environment.
• Low ego and team spirit mindset.
• Your application will be all the more interesting if you also have:
• First-hand Vespa (or equivalent large-scale information retrieval) experience.
• Experience building or operating MCP servers / tool-serving infrastructure for LLMs.
• Familiarity with knowledge graphs, RDF / SPARQL, or large structured databases (PostgreSQL, ClickHouse, DuckDB...).
• Experience with large bare-metal infrastructure or HPC environments.

We offer a comprehensive benefits package designed to support your well-being, growth, and work-life balance. Benefits vary by country and may include healthcare coverage, parental leave, retirement plans, relocation support, wellness programs, meal and transportation allowances, and other location-specific perks. For the most up-to-date details on benefits available in your location, please refer to our Benefits page.

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