{"library":"Flask","type":"library","category":null,"description":"Lightweight WSGI web framework. Current version is 3.1.3 (Feb 2026). Flask 3.0 (Sep 2023) removed a large set of APIs that had been deprecated since 2.x — before_first_request, FLASK_ENV, JSON config keys, and custom json_encoder/decoder. LLMs still generate these removed patterns.","language":"python","status":"active","version":"3.1.3","tags":["web","wsgi","framework","http","jinja2","werkzeug"],"last_verified":"Tue Jun 09","install":[{"cmd":"pip install Flask","imports":["from flask import Flask\napp = Flask(__name__)","# Use app context or lifespan pattern\nwith app.app_context():\n    init_db()\n\n# Or with app factory + teardown:\n@app.before_request\ndef check_initialized():\n    ..."]},{"cmd":"pip install \"Flask[async]\"","imports":[]},{"cmd":"pip install \"Flask[dotenv]\"","imports":[]}],"homepage":"https://flask.palletsprojects.com","github":"https://github.com/pallets/flask","docs":"https://flask.palletsprojects.com/","changelog":"https://flask.palletsprojects.com/page/changes/","pypi":"https://pypi.org/project/Flask/","npm":null,"openapi_spec":null,"status_page":null,"smithery":null,"compatibility":{"summary":{"python_range":"3.10–3.9","success_rate":100,"avg_install_s":2.2,"avg_import_s":0.46,"wheel_type":"wheel"},"url":"https://checklist.day/v1/registry/Flask/compatibility"}}