Flask review
A small Python backend framework that leaves component choices to the developer.
Reviewed by iTechGuides Editors · Editorial team · Updated Oct 2026
Flask is an open-source Python backend framework for building web applications and services. It is suited to developers and teams who want a small core and prefer to choose which components to add, rather than start with a framework that bundles an ORM or authentication system. Its listed capabilities cover URL routing to application views, request and response handling, Jinja templates, cookie-based sessions, and a development server and debugger. Flask is a framework or library for self-hosted deployment, not a hosted software service.
The main trade-off is breadth. Flask supplies core web application building blocks and an extension mechanism, rather than including every application component in the framework. In particular, an ORM and built-in authentication are not part of its stated feature set. That can suit projects with specific component preferences, but teams looking for those capabilities bundled into the framework should weigh whether choosing and adding extensions fits their approach. The framework's hybrid rendering modes include Jinja template integration, while its primary language is Python.
Flask is open source and has a free offering, with no vendor pricing plan described. Its fit across solo, small, mid-market, and enterprise company sizes does not change the core trade-off: the framework keeps its built-in scope lean, and developers choose how to extend it. The development server and debugger support development, while deployment is self-hosted. Choose Flask if Python, a small framework core, and control over component selection are priorities. Consider an alternative if you need an ORM or authentication included as standard, or prefer a framework with a broader built-in feature set.
Flask pros and cons
- Where it wins
- Provides URL routing and request and response handling.
- Integrates Jinja templates and supports cookie-based sessions.
- Keeps the core small and can be extended through Flask extensions.
- Where it doesn't
- Does not include an ORM.
- Does not include built-in authentication.
- Its feature set is comparatively lean; added functionality depends on extensions.
Flask fact sheet, pricing and score →
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