{"id":23953,"library":"langflow","title":"Langflow","description":"Langflow is a low-code Python package for building AI agents and RAG applications through a visual flowchart interface. Version 1.9.1 is the latest; the project follows a monthly release cadence. It supports Python >=3.10 and includes a built-in web application for drag-and-drop workflow design.","status":"active","version":"1.9.1","language":"python","source_language":"en","source_url":"https://github.com/langflow-ai/langflow","tags":["low-code","ai-agents","rag","visual-programming","fastapi"],"install":[{"cmd":"pip install langflow","lang":"bash","label":"Install from PyPI"},{"cmd":"pip install langflow[all]","lang":"bash","label":"Install with all extras"}],"dependencies":[{"reason":"Required to run the FastAPI-based web server","package":"uvicorn","optional":false},{"reason":"Core web framework for the API","package":"fastapi","optional":false},{"reason":"ORM for database operations","package":"sqlmodel","optional":false}],"imports":[{"note":"Direct import of module does not expose the main class; use from langflow import Langflow","wrong":"import langflow","symbol":"Langflow","correct":"from langflow import Langflow"},{"note":"The start function moved in v1.0+ to the top-level package","wrong":"from langflow.server import start","symbol":"start","correct":"from langflow import start"}],"quickstart":{"code":"from langflow import start\n\n# Start Langflow server on default port 7860\nstart(\n    host=\"127.0.0.1\",\n    port=7860,\n    open_browser=False,\n    components_path=\"./components\",\n    log_level=\"INFO\"\n)","lang":"python","description":"Start the Langflow web application programmatically. The server will be accessible at http://127.0.0.1:7860."},"warnings":[{"fix":"Use `from langflow import start` or `from langflow import Langflow`.","message":"In v1.0, the import path for the main entry point changed from `langflow.server` to `langflow`. Old code `from langflow.server import app` will fail.","severity":"breaking","affected_versions":"v1.0+"},{"fix":"Use `langflow serve` or call `start()` from Python.","message":"The `langflow run` CLI command is deprecated in favor of `langflow serve` or the Python API.","severity":"deprecated","affected_versions":">=1.5.0"},{"fix":"Set the `LANGFLOW_DATABASE_URL` environment variable to a PostgreSQL database for production.","message":"Langflow stores flow data in a SQLite database by default; it is not thread-safe for multiple processes. Running multiple workers may cause database corruption.","severity":"gotcha","affected_versions":"all"},{"fix":"Run `playwright install chromium` after installing Langflow.","message":"When using Playwright for headless browser automation, ensure the Playwright browsers are installed (e.g., `playwright install chromium`). Missing browsers cause `RuntimeError: Could not find browser revision`.","severity":"gotcha","affected_versions":">=1.8.0"}],"env_vars":null,"last_verified":"2026-05-01T00:00:00.000Z","next_check":"2026-07-30T00:00:00.000Z","problems":[{"fix":"Change `from langflow.server import app` to `from langflow import start`.","cause":"Import path changed in v1.0; old import no longer exists.","error":"ModuleNotFoundError: No module named 'langflow.server'"},{"fix":"Run `playwright install chromium` in your terminal.","cause":"Playwright browsers are not installed alongside the Python package.","error":"RuntimeError: Could not find browser revision. Please run `playwright install`."},{"fix":"Set `LANGFLOW_DATABASE_URL` to a PostgreSQL connection string, e.g., `postgresql://user:pass@localhost:5432/langflow`.","cause":"Multiple processes (e.g., multiple Uvicorn workers) accessing the default SQLite database concurrently.","error":"sqlalchemy.exc.OperationalError: (sqlite3.OperationalError) database is locked"}],"ecosystem":"pypi","meta_description":null,"install_score":null,"install_tag":null,"quickstart_score":null,"quickstart_tag":null}