Libraries & Extensibility

Built-in standard libraries

Ship with Robot Framework (Python stdlib-backed). Common ones:

Library	Purpose
`BuiltIn`	Control flow helpers, logging, assertions (implicit)
`Collections`	List/dict utilities
`String`	Text manipulation
`OperatingSystem`	Files, paths, process spawning
`DateTime`	Dates and times
`XML`	XML parsing and validation

*** Settings ***
Library           Collections
Library           String

*** Test Cases ***
Collections Example
    ${items}=    Create List    a    b
    Append To List    ${items}    c
    Length Should Be    ${items}    3

External libraries (ecosystem)

Library	Purpose	Install (typical)
`SeleniumLibrary`	Classic browser UI (WebDriver)	`pip install robotframework-seleniumlibrary`
`Browser`	Modern UI via Playwright	`pip install robotframework-browser`
`RequestsLibrary`	HTTP / REST	`pip install robotframework-requests`
`DatabaseLibrary`	DB access	`pip install robotframework-databaselibrary`
`SSHLibrary`	Remote shell / SFTP	`pip install robotframework-sshlibrary`

Verify each project’s PyPI name and version against your Python environment; pin versions in CI.

Custom Python libraries

Style	When to use
Static	Simple module: functions become keywords by name
Dynamic	`get_keyword_names` + `run_keyword`—meta-programming, RPC-style
Hybrid	Class-based with attributes for doc-driven behavior

Example: static API with `@keyword`

from robot.api.deco import keyword


@keyword("Multiply ${a} By ${b}")
def multiply_by(a: float, b: float) -> float:
    return float(a) * float(b)

*** Settings ***
Library    ../libs/math_ops.py

*** Test Cases ***
Use Custom Keyword
    ${p}=    Multiply ${2} By ${3}
    Should Be Equal As Numbers    ${p}    ${6}

Importing in `* Settings *`

*** Settings ***
Library           SeleniumLibrary    timeout=10s    run_on_failure=Capture Page Screenshot
Library           Browser    timeout=30s
Resource          keywords/login.resource
Variables         config/stage.yaml

Library — Python module or class path.
Resource — another .robot / .resource file (keywords and variables).
Variables — variable file (Python dict/list, YAML, etc., per setup).

Remote library interface

Remote libraries run keywords on another process or host via XML-RPC—useful for legacy stacks, constrained environments, or sharing one heavy dependency. You start a remote server wrapping a real library, then import Remote with the URI.

*** Settings ***
Library           Remote    http://127.0.0.1:8270    WITH NAME    LegacySvc

Treat remote calls like network I/O: timeouts, retries, and security (TLS, auth) matter.

Library scope

Control how library instances are reused with ROBOT_LIBRARY_SCOPE on the class:

Scope	Behavior
`TEST`	New instance per test (default for many libs)
`SUITE`	One instance per suite file
`GLOBAL`	Single instance for whole run

class ExampleLib:
    ROBOT_LIBRARY_SCOPE = "SUITE"

    def __init__(self) -> None:
        self._state = 0

Use SUITE or GLOBAL only when expensive setup is safe to share and isolation is still acceptable.

Quick selection guide

Need	Direction
Reusable Robot vocabulary	`.resource` + user keywords
Non-trivial logic / I/O	Python library
Third-party protocol (HTTP, browser, DB)	Mature Robot library first
Cross-language or remote system	Remote library or dedicated service + thin Robot wrapper