Overview
HTTP or API automation communicates directly with a server. It sends structured requests and receives structured responses. Once the correct request format is known, this can be fast and inexpensive. It is well suited to retrieving page contents, calling documented services, submitting known operations, or running repeatable integrations in the background.
Its weakness is narrowness. The request must match the service's expected schema, authentication, parameters, and sequence. A flow built for one service may not transfer to another. Dynamic interfaces, undocumented endpoints, anti-automation controls, and changing request formats can make direct automation fragile. Reading documentation before attempting a non-trivial platform reduces avoidable errors.
Browser automation operates the rendered interface. It can open a page, inspect elements, click controls, fill forms, navigate JavaScript-driven applications, and capture screenshots. This makes it much more general than a custom HTTP flow. It can handle tasks where the user interface is the only practical specification.
The cost is speed. A browser agent often performs one visible action at a time and may need to inspect the page between actions. It consumes more tool calls and more context than one direct request. Browser sessions can also fail because of stale processes, authentication state, changing page structure, or automation detection.
Computer automation controls the mouse and keyboard across the operating system. It can use applications and local interfaces that do not expose a browser or API path. It is the most general layer because it can attempt nearly anything a person can do on the machine.
It is also the slowest and most expensive layer. The agent must repeatedly inspect screenshots, infer interface state, move the pointer, type, and verify the result. Small visual or state errors can require many corrective steps.