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Learn Apify's conventions for actor-build number and how to use a specific Actor version in a run. Understand an Actor's lifecycle and manage its cache.

Before the Actor can be run, it first needs to be built. The build effectively creates a snapshot of a specific version of the Actor's settings, such as the Source code and Environment variables. It creates a Docker image that contains everything the Actor needs for its run, including necessary NPM packages, web browsers, etc.

Each build is assigned a unique build number of the form MAJOR.MINOR.BUILD (e.g. 1.2.345), where MAJOR.MINOR corresponds to the Actor version number (see Versioning), and BUILD is an automatically-incremented number starting at 1.

By default, the build has a timeout of 300 seconds and consumes 4096 MB (2048 MB on the free plan) of memory from the user's memory limit. See the Resource limits section for more details.


In order to enable active development, the Actor can have multiple versions of the source code and associated settings, such as the Base image and Environment. Each version is denoted by a version number of the form MAJOR.MINOR; the version numbers should adhere to the Semantic Versioning logic.

For example, the Actor can have a production version 1.1, a beta version 1.2 that contains new features but is still backward compatible, and a development version 2.0 that contains breaking changes.


When running the Actor, the caller needs to specify which build should actually be used. To simplify this process, the builds can be associated with a tag such latest or beta, which can be used instead of the version number when running the Actor. The tags are unique - only one build can be associated with a specific tag.

To set a tag for builds of a specific Actor version, set the Build tag property. Whenever a new build of the version is successfully finished, it is automatically assigned the tag. By default, the builds are set to the latest tag.


By default, the build process pulls the latest copies of all necessary Docker images and builds each new layer of Docker images from scratch. To speed up the builds triggered via API, you can add useCache=1 parameter. See the API reference for more details.