Python Developer - Risk and Data

JUXT; Greater London; On-site; GBP 90,000 - 140,000; Full time

Job summary

JUXT is partnering with a leading global commodities trading firm to build a new core data platform for real-time and end-of-day market data. This greenfield build replaces an existing system with a scalable cloud-native solution, handling ingestion from many market data providers and exposing familiar APIs to keep client applications working unchanged.

You’ll collaborate with senior engineers to plan migration, deploy new systems, monitor traffic, and iterate quickly.

Qualifications

• 5+ years in backend/data platform roles.
• Experience with scalable cloud data systems.
• Familiar with API fidelity and proxies.
• Strong testing and validation practices.
• Ability to work closely with a client in a small team.

Responsibilities

• Build feed ingestion subsystems from external data providers.
• Develop query APIs using ClickHouse and S3 Tables/Iceberg.
• Create interception proxy to route traffic while maintaining API compatibility.
• Analyze traffic, validate designs with real client requests.
• Ensure observability with logs, metrics, traces; configure AWS/Grafana.

Skills

Senior backend engineer

Data pipelines

Networking fundamentals

AWS/cloud data platforms

Testing discipline

Autonomy & communication

Tools

AWS

ClickHouse

Airflow

Envoy

Grafana

S3

Job description

JUXT is partnering with a leading global commodities trading firm to build its new core data platform for real-time and end-of-day market data.

During this mission we’ll replace an existing system with a new highly scalable cloud-native data platform, without breaking client applications that rely on this data today. We’ll build new data ingestion pipelines to consume from a wide variety of market data providers. We will also build new query capabilities that are compatible with existing APIs, so that client applications keep working unchanged.

This is a greenfield build with a pragmatic team that likes to prove solutions quickly and iterate. You’ll work alongside highly experienced engineers to plan the migration, build and deploy new systems, analyse existing traffic and prioritise, then expand feeds and query APIs to cover new use-cases.

What you’ll work on

• Building the feed ingestion subsystem: event-driven connectors pulling data directly from external market data providers.
• Building query APIs using modern scalable data technologies like Clickhouse and S3 Tables/Iceberg with Athena. Experience with other massively scalable data tech is beneficial (QuestDB, Snowflake, DuckDB).
• Building an intercepting proxy to intelligently direct traffic towards new query services. Achieving faithful API compatibility so that clients can continue to operate correctly.
• Gathering and analysing metrics and request payloads to discover and survey existing data clients. Validating the design end-to-end against real client requests, and rolling out new systems in carefully staged steps.
• End-to-end observability across every component: logs, metrics and traces into ClickStack and Grafana, augmented by AWS observability services.
• Working carefully to guide the client, learning through discovery sessions, and thinking carefully about platform architecture (streaming vs request-response use cases, staged and low-risk roll-outs, tracking data licenses, high-frequency feed downsampling).

Tech stack you’ll be working with

• Data platform: AWS (S3, S3 Tables, Athena), ClickHouse, Airflow.
• Interception and networking: Envoy, DNS, TLS, X.509, internal CAs.
• Ingestion: event-driven services, and market data sources.
• Observability: ClickStack, Grafana, AWS observability services.
• AI tools: AI-assisted development with recent models is a normal part of how we work.

What we’re looking for

• A strong senior backend engineer, comfortable across the languages in play on a data platform (primarily Python; languages like Java, Golang Rust, are a bonus) and experienced in building production data-intensive services.
• Real experience with data pipelines and event-driven ingestion: connectors, schedulers, idempotency, backfill, and the operational care that feeds demand.
• Solid networking fundamentals: DNS, TLS and certificates, OSI model, TCP packet analysis, HTTP proxying — enough to reason confidently about a transparent interception layer and debug it when reality intrudes.
• Experience with scalable cloud data platforms, ideally AWS: object storage, table formats, query engines.
• Strong testing discipline. Validation, reconciliation, and careful roll-out.
• High autonomy and clear communication: a small senior team, embedded with the client, making pragmatic decisions and explaining them well. You will need to take ownership of significant tasks, design solutions and deliver.

Who this role suits

This suits an engineer who likes owning a hard problem end-to-end and building end-to-end prototypes to prove solutions quickly. You need experience across many platform architectures and network configurations, as the project combines systems work (transparent proxying, TLS, API fidelity) and data platform work (feeds, storage, serving). You’ll be well-connected to measures of progress (real traffic served, real use-cases migrated to the new data platform). You should be comfortable in a small, senior, high-trust team working directly with a client.