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Dynamic Report Generator

Backend service that dynamically generates professional Excel reports from JSON templates and live API data, powering 40+ document workflows.

PythonFastAPIOpenPyXLPandasAWS S3Docker

What it does

A specialized FastAPI service that generates complex, styled Excel reports by merging JSON-based templates with live data from multiple backend APIs — turning what used to be hours of manual work into an API call.

Architecture highlights

  • Template-driven architecture with JSON configurations defining worksheets, tables, columns, formulas, and styling
  • Dynamic Excel formula generation with cross-sheet cell references and row-relative placeholders
  • Reference tracking system that resolves named references to actual cell coordinates across worksheets
  • Professional styling engine with configurable fonts, colors, borders, alignment via JSON style templates
  • Pandas/NumPy data transformation layer for financial calculations and aggregation
  • AWS S3 integration for file storage with pre-signed URL generation
  • Supports 40+ report types with varied layouts, formulas, and data sources

Backend patterns

  • Async FastAPI with background task support for long-running generation jobs
  • Chunked processing for large datasets (1000+ row threshold) to manage memory
  • Header forwarding for downstream API authentication across microservices
  • Multi-environment CI/CD with GitHub Actions deploying to dev, QA, staging, and production
  • Docker containerization with Alpine Python for minimal image size
  • OpenPyXL for low-level Excel manipulation: formulas, conditional formatting, image embedding, table creation