You will get production-ready FastAPI bug fixes with validation and regression tests
Project details
A FastAPI endpoint can look fixed and still fail on malformed input, database edge cases, or the next release. I provide a production-focused repair: reproduce the defect, trace its root cause through routing, validation, dependencies, database sessions, exception handling, and serialization, correct the code path, and prove the behavior with Pytest.
As founder of Hannes Software, I build and maintain public commercial products with Python, FastAPI, OpenAPI, SQLAlchemy/Alembic, SQLite, SvelteKit integrations, automated testing, and CI/CD. I also designed HSB, a full-stack workflow automation platform with durable work items, browser/email integrations, retry/recovery, and evidence-backed audit trails.
You receive a reviewable patch, predictable HTTP status codes and JSON errors for the touched paths, targeted regression coverage, verification notes, and a clean handoff—not an unexplained change.
This service is for an existing, locally runnable FastAPI codebase. Choose a tier by the related defects and endpoints in one bounded workflow. New features, broad rewrites, cloud infrastructure, deployment, and unrelated frontend work require a separate scope.
As founder of Hannes Software, I build and maintain public commercial products with Python, FastAPI, OpenAPI, SQLAlchemy/Alembic, SQLite, SvelteKit integrations, automated testing, and CI/CD. I also designed HSB, a full-stack workflow automation platform with durable work items, browser/email integrations, retry/recovery, and evidence-backed audit trails.
You receive a reviewable patch, predictable HTTP status codes and JSON errors for the touched paths, targeted regression coverage, verification notes, and a clean handoff—not an unexplained change.
This service is for an existing, locally runnable FastAPI codebase. Choose a tier by the related defects and endpoints in one bounded workflow. New features, broad rewrites, cloud infrastructure, deployment, and unrelated frontend work require a separate scope.
Programming Languages
JavaScript, Python, TypeScriptCoding Expertise
Performance Optimization, SecurityWhat's included
| Service Tiers |
Starter
$49
|
Standard
$119
|
Advanced
$249
|
|---|---|---|---|
| Delivery Time | 3 days | 5 days | 7 days |
Number of Revisions | 1 | 2 | 2 |
Bug Investigation | |||
Fix Documentation | |||
Detailed Code Comments | - |
Frequently asked questions
About Han
Full-Stack & Desktop Engineer | FastAPI, C++/Qt, Rust/Tauri
Huanggang, China - 5:07 pm local time
I help founders and engineering teams finish software that is stuck between “working prototype” and “reliable product.” I can enter an existing codebase, reproduce the failure, identify the real boundary at fault, implement the change, add regression coverage, and carry it through packaging and release.
FAST FACTS
• 10 public commercial products shipped
• 3 years of C++ development
• 70 MB A2L parsing reduced from ~30 minutes to ~4 minutes
• Embedded scheduling error measured within ±20 μs
• Windows, Linux, web, GitHub Releases, Microsoft Store, and direct installers
• Product ownership from architecture and UX through CI/CD and support
FULL-STACK & API ENGINEERING
Python, FastAPI, REST/OpenAPI, SQLAlchemy, Alembic, SQLite, authentication, scheduled jobs, third-party integrations, Pytest, Svelte/SvelteKit, and TypeScript. I build API-backed products, internal tools, durable workflows, and maintainable frontend/backend boundaries.
CROSS-PLATFORM DESKTOP & SYSTEMS
C++/Qt, Rust/Tauri, embedded Linux, C#/WPF, native integrations, IPC, networking, persistence, performance profiling, and Windows/Linux packaging. I work comfortably across UI, application logic, platform code, and release infrastructure.
LOCAL AI & AUDIO PRODUCTS
I integrate existing models into real applications: preprocessing, ONNX Runtime inference, post-processing, latency and memory control, failure handling, editable UI state, and export pipelines. My commercial audio work includes source separation, transcription, pitch/timing analysis, and low-latency practice workflows. The value is not a model demo—it is a usable, packaged product around the model.
WORKFLOW AUTOMATION & APPLIED AI
For HSB, I designed and built a FastAPI/SvelteKit platform with OpenAPI clients, durable work items, shared account pools, browser and email integrations, LLM-assisted research/review, screenshot chunking, page-state classification, coordinate targeting, human handoff, retries, recovery, and evidence-backed audit trails.
DELIVERY & RELEASE ENGINEERING
GitHub Actions CI/CD, automated tests, version and catalog gates, Windows/Linux installers, canonical release artifacts, SHA-256 verification, release manifests, GitHub Releases, Microsoft Store distribution, documentation, and production support.
BEST-FIT PROJECTS
• Existing FastAPI, Svelte, C++/Qt, or Rust/Tauri application rescue
• API modules, integrations, internal tools, and workflow automation
• Desktop performance, native integration, packaging, and release failures
• Local ONNX/AI or audio features inside an existing product
• CI/CD, installers, and launch-readiness hardening
I start with reproduction steps and acceptance criteria, then deliver reviewable code, regression evidence, build artifacts, and a concise handoff. Send me the stack, current blocker, target platform, and definition of done; I will propose the first safe milestone.
Steps for completing your project
After purchasing the project, send requirements so Han can start the project.
Delivery time starts when Han receives requirements from you.
Han works on your project following the steps below.
Revisions may occur after the delivery date.
Reproduce the defect
Run the supplied revision and sanitized configuration, reproduce the reported behavior, and record the failing request and response path.
Trace the root cause
Follow routing, dependencies, validation, database/session logic, exception handling, and serialization to identify the actual failure point.