Framework Upgrade

Upgrade FastAPI Automatically

Upload your project and get production-ready migrated code in minutes.

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What changes between FastAPI (older) and FastAPI (latest)?

  • Pydantic v2 migration: BaseModel.dict() renamed to model_dump(), .json() to model_dump_json()
  • Pydantic v2 validators: @validator replaced by @field_validator, @root_validator by @model_validator
  • Pydantic Config class replaced by model_config = ConfigDict(...) attribute
  • Starlette upgrades may change middleware signatures and request/response APIs
  • Deprecated: status_code in response_model_include; use separate parameter
  • on_event lifecycle deprecated in favor of lifespan context manager pattern
  • OpenAPI schema generation changes for Optional fields and Union types
  • Type annotation improvements: Annotated[type, Query()] pattern now preferred

How Nivo migrates FastAPI (older) to FastAPI (latest)

01

Connect your project

Paste a GitHub URL or upload a ZIP file of your FastAPI (older) project.

02

Nivo detects your FastAPI (older) project

The engine scans your codebase to identify FastAPI (older) patterns, APIs, and configuration that need updating.

03

AI applies all FastAPI (latest) migration transforms

Hybrid AST + AI engine applies deterministic transforms for configuration and dependencies, and AI-powered transforms for complex code changes. Every change gets a confidence score.

04

Download migrated codebase + review report

Get a ZIP with your fully migrated code, a complete migration report, and a checklist of items flagged for manual review.

Frequently Asked Questions

What is the hardest part of upgrading FastAPI?

The Pydantic v1 to v2 migration is typically the most involved part. Every model using .dict(), .json(), @validator, or Config inner classes needs updating. Nivo handles all of these transformations automatically across your entire codebase.

Is it safe to upgrade FastAPI in production?

Yes. Nivo transforms Pydantic models, validator decorators, and deprecated FastAPI patterns while preserving your API behavior. Each file produces a reviewable diff so you can verify changes before deploying.

How long does a FastAPI upgrade take?

Most projects complete in under 10 minutes. The migration primarily involves Pydantic model updates and deprecated parameter replacements. Nivo processes all Python files in parallel.

Do I need to update my database ORM (SQLAlchemy)?

FastAPI itself does not mandate a SQLAlchemy version, but Pydantic v2's ORM mode has changed to from_attributes=True in ConfigDict. Nivo updates these ORM integration patterns automatically.

Will my test suite still pass after the upgrade?

Nivo updates TestClient imports and deprecated test patterns alongside production code. Your existing pytest fixtures and API tests should work after the migration with only the updated method names.

Start your FastAPI (older) to FastAPI (latest) migration

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