Backend Engineer for SaaS MVP

We’re building a lean SaaS MVP focused on precise data processing, reconciliation, and automated reporting.
We need a backend engineer who can implement a deterministic calculation engine with strong auditability.

Responsibilities:

Implement the core calculation engine (aggregating values, applying fees/rules, generating outputs).

Build clean REST APIs (FastAPI or Django REST) for data ingestion and reporting.

Handle structured file imports (CSV/Excel) with reusable mapping templates.

Ensure deterministic, decimal-accurate calculations (no tolerance for rounding errors).

Produce PDF reports programmatically (WeasyPrint / ReportLab).

Implement audit trail (inputs, outputs, versioning, errors).

Requirements:

Python (FastAPI or Django REST Framework).

experience with decimal.Decimal (mandatory) and PostgreSQL NUMERIC types.

Proficiency with Pandas or similar for processing large CSV/Excel datasets.

Knowledge of testing (pytest, fixtures) and reproducible pipelines.

Clear English communication, ability to document APIs and logic.

Nice to Have:

Background in financial, accounting, or reconciliation systems.

Experience generating structured PDF/Excel reports.

Basic Docker/DevOps familiarity.

Engagement:

Remote, milestone-based.

All work under NDA, IP fully assigned.