Python Engineer, Financial Data Platform & Integrations

Cardiff; Cardiff; Hybrid; GBP 70,000 - 110,000; Full time

Benefits offered by this job

Medical, dental, and vision coverage

401(k) plan

Flexible PTO

Job summary

Cardiff is seeking a Python backend engineer to own data integrations and FastAPI services that deliver financial and credit data to internal teams. You will build provider integrations (Experian, Plaid, bank sources) and AWS-based ETL pipelines, ensuring data quality and regulatory compliance.

You’ll work in a small, independent team with ownership from day one and opportunities to advance toward full-time.

Qualifications

• 5+ years of Python backend engineering on data-intensive systems.
• Production backend services built and operated in a modern Python framework (FastAPI preferred).
• Hands-on Snowflake experience in production.
• AWS data services for pipelines (Glue, Athena, S3, Step Functions, Lambda).
• Strong data modeling, schema alignment, and transformation instincts.

Responsibilities

• Design, build, and run FastAPI services exposing financial and credit data to internal consumers.
• Own integration layer with external providers (Experian, Plaid, bank sources): retries, backoff, rate limits, credential handling.
• Build pipelines landing provider data in Cardiff's systems (Snowflake, serverless ETL on AWS).
• Perform data modeling and schema mapping with domain experts and analysts.
• Ensure security, privacy, and regulatory obligations are met; validate model outputs before they enter pipelines.
• Apply LLM APIs for extraction/classification with output validation.

Skills

Python

FastAPI

SQL

Pandas

Data modeling

Tools

Snowflake

AWS Glue

AWS Athena

AWS Step Functions

AWS S3

AWS Lambda

Job description

About Cardiff

Cardiff lends to small businesses. Since 2004 we've funded more than $12.4 billion across the country, to businesses in logistics, healthcare, construction, professional services, and plenty in between. We're building our own underwriting technology, and we still answer the phone; our customers need capital fast, and they want a straight answer from a person who can actually help.

Why this role matters

Cardiff's underwriting decisions are only as good as the data behind them. This role owns that layer: the integrations that pull credit and bank transaction data from providers like Experian and Plaid, and the Python services that deliver it to the systems driving risk decisions. We're pushing funding turnaround from 24 business hours toward minutes, and that only works if the data underneath is fast, reliable, and compliant. As we expand ML-based decisioning and LLM-based workflows, this layer sets the pace for everything built on top of it.

The role

This is a Python backend engineering role focused on financial data integration. You'll build and maintain the FastAPI services that deliver financial and credit data to Cardiff's internal systems, along with the provider integrations and AWS pipelines that feed them.

You'll work as an individual contributor on Cardiff's technology team, alongside the Lead AI Architect and engineers covering full-stack, UI, and operations, with access to our AI platform from day one and real ownership over how you get the work done.

The role starts as an ongoing contract with a clear path to full-time; we begin with a contract so both sides can evaluate fit through real work, and your scope will grow as you show you can carry more.

What success looks like

In your first 90 days, you will:

• Ship at least one production integration with a financial or credit data provider (Experian, Plaid, or a bank transaction source) end to end
• Implement automated validation and quality checks across the pipelines you own, so failures surface before they reach downstream consumers
• Ship or materially extend a FastAPI service that exposes provider data internally, with tests and documentation another engineer can pick up cold
• Deliver a documented data model and schema mapping for at least one provider domain, built alongside our domain experts and analysts
• Demonstrate one LLM-assisted extraction workflow on unstructured input (bank statements, credit memos), with output validation in place

By the end of your first year:

• The financial data layer is Cardiff's system of record: accurate, current, and complete enough that underwriting, risk, and operations decide on it with confidence
• Adding or replacing a data provider is a well-worn path rather than a project; the business can move on partnerships without waiting on engineering
• Compliance is a property of how the systems are built, not a scramble ahead of each review

What you'll do

• Design, build, and run the FastAPI services that expose financial and credit data to internal consumers: API design, auth, versioning, pagination, and clear error handling
• Own the integration layer with external providers (Experian, Plaid, bank transaction sources): retries, backoff, rate limiting, credential handling, and graceful degradation when a provider slows down or goes dark
• Build the pipelines that land provider data in Cardiff's systems, including Snowflake, using serverless ETL on AWS (Glue, Athena, Step Functions, S3 data lakes), supporting both batch and near-real-time ingestion
• Do the data modeling and schema mapping that keeps disparate provider formats semantically consistent, working with our domain experts and analysts
• Build integrations that meet Cardiff's security, privacy, and regulatory obligations, with Legal, Compliance, and Security owning final interpretation and sign-off
• Apply LLM APIs for extraction and classification of unstructured documents where it earns its keep, with model outputs validated before they enter the pipeline
• Make AI tooling part of how you build, and read what it produces before it ships
• Maintain the unit tests, integration tests, and documentation for every component you own

What we're looking for

• 5+ years of Python backend engineering on data-intensive systems, with the emphasis on recent, demonstrable work
• Production backend services built and operated in a modern Python framework (FastAPI preferred; Flask or Django fine), including API design, auth, testing, and async programming
• Reliable third-party API integration (retries, idempotency, rate limits, partial failures, observability), ideally against financial APIs from credit bureaus, banks, or payment processors
• Substantial hands-on Snowflake experience in production: loading, modeling, and large-scale querying
• AWS data services for pipeline orchestration (Glue, Athena, S3, Step Functions, Lambda), including data lake layouts and partitioning that keep querying cost-efficient
• Strong data modeling, schema alignment, and transformation instincts
• A working grasp of API authentication, encryption, and the compliance requirements that come with regulated financial data
• Proficiency in SQL and Pandas

Nice to have

• Credit decisioning, loan underwriting, or financial risk data experience
• LLM APIs (Claude, OpenAI, or equivalent) applied to extraction, classification, or summarization, plus the applied-LLM toolkit: prompt design, evals, output validation, RAG and embeddings
• AI-assisted development tools (Claude Code, Cursor, Codex, Devin) as a primary mode of building
• CI/CD pipelines

Who does well here

You ship: a working v1 today beats a polished v1 next month. You sweat data correctness, because bad data that looks fine is the most expensive failure in a lending business. You treat AI tooling as a force multiplier, and you know when to trust the output and when to override it. You work independently and communicate proactively; when something is blocked, you say so the same day.

This role may not be a fit if you

• Prefer structured corporate environments with clear lanes
• Want detailed direction before you start
• Would rather maintain systems than build them

Benefits

• Medical, dental, and vision coverage
• 401(k) plan
• Flexible PTO and observed holidays
• Remote-first, with support for your home-office setup

Cardiff, Inc. is an Equal Opportunity Employer. We are committed to creating a diverse and inclusive workplace and do not discriminate on the basis of race, color, religion, sex, national origin, age, disability, veteran status, sexual orientation, gender identity, or any other characteristic protected by applicable law.