Read the canvas: blocks, wires & editable Python
Goal. Understand how a flow works: drag blocks onto the canvas, wire them together, and see that every block is real Python you can open.
Drag a Chat Input, a Language Model, and a Chat Output onto the canvas, then wire them left-to-right so a typed message flows into the model and the reply flows out.
Build it on the same Simple Agent flow or a blank one — Langflow is a visual front end over Python and LangChain, so wiring blocks is the same as composing those steps in code.
- 1A flow is blocks wired together: each block does one job — a chat input, an LLM, a document store, an agent, a web-fetch tool — and the wires between them decide how information moves through the app.
- 2Drag blocks from the component list onto the canvas and connect their ports left to right. Wiring is how you design behaviour — no glue code required for the common cases.
- 3Open any block to see it's real, editable Python underneath. Beginners never have to touch it, but it's there when you want to customise a component or understand exactly what a step does.
You'll see. A small flow you assembled by hand — input → model → output — that responds when you open the Playground.
Cost. Still free: building and running flows locally costs nothing beyond your own machine and the model key you call.
Takeaway. Langflow is a visual layer over Python/LangChain — you design with blocks and wires, and drop to code only when you choose to.