modal

Overview

This is a foundational skill for working with the Modal cloud platform.

Modal is a platform for AI workloads. It offers highly scalable serverless compute (including GPUs) with minimal configuration.

Using the CLI or running code that depends on the modal library requires internet access and an authorization token. There is no "local development mode" with Modal.

Documentation

The official docs are the best source for up-to-date information on the platform. Make use of them when planning, debugging, or answering questions!

Modal's latest documentation, which may cover features introduced in newer SDK versions, is outlined at https://modal.com/llms.txt. This file contains titles and URLs for all public docs; reading it directly will guide you to specific content. Fetch the docs using a .md extension to get plain text.

When installed via the Modal CLI, this skill installs local documentation in references/ unless --no-docs is passed:

• api/: An API reference generated locally from the signatures and docstrings of the SDK used to install or update the skill.
• guide/ and examples/: Guides and examples downloaded from the online docs. These reflect the website at download time and may cover features unavailable in that SDK version.

You can also refer to https://modal.com/llms-full.txt, which aggregates all docs in a single very large file. Do not read this into your main context, but it may be useful for searching.

Using the CLI

The modal CLI can be used to run or deploy code, manage resources, and observe running Apps. It is a key tool for interacting with Modal throughout all stages of development.

Run modal --help to see all available CLI commands.

You can see more detailed information about each command by running modal [command] --help. Rely on the --help to discover functionality: new features are added in every release! Always check the --help if you encounter a usage error.

Tip: many CLI commands accept a --json flag to make their output more easily parseable, e.g. with jq.

The modal CLI is part of the Python SDK and executes in a Python runtime. Depending on the user's preferred Python development workflow, you may need to prefix modal CLI invocations with, e.g., uv run to ensure a consistent Python environment. The CLI can also be used via uvx as a standalone tool, but only do this when working outside of a Python project.

Do not run Modal CLI commands with an attached terminal (TTY/PTY), so logs appear as plain text rather than spinner redraws.

Getting up to date

You have significant knowledge about Modal from your training data but may not be aware of new features or recent changes to the API. Modal is continuously adding new features. Reading relevant docs while planning or debugging can help you discover the most up-to-date way to accomplish a task on Modal.

The Modal CLI provides a modal changelog command for learning about recent changes. Useful invocation patterns:

• modal changelog --since [DATE] to see changes added since your knowledge cutoff
• modal changelog --since [VERSION] when migrating a codebase to a newer version
• modal changelog --newer to discover features that would be available on update

Note: the output of modal changelog may be long. Do not load it fully into your context.

Run modal --version to see the SDK version that is in use.

If your code exercises deprecated APIs, Modal will issue warnings. Use the warning message and related documentation to migrate your code to stable API.

Before using this skill, check that its version in the metadata is identical to modal --version. If not, run modal skills update to update it, passing --claude if this skill lives under a .claude/ directory and --global if it lives under the home directory rather than the project.

Async Python

When writing async Python, use Modal's .aio() interface (e.g. await modal.Sandbox.create.aio(...), await modal.Function.remote.aio(...)) so that Modal runs its I/O operations via asynchronous coroutines.

Other languages

Python is currently the only runtime language for Modal Functions, but there are Modal SDKs in both JavaScript (TypeScript) and Go:

• JavaScript SDK: https://modal.com/docs/sdk/js/latest/intro.md
• Go SDK: https://modal.com/docs/sdk/go/latest/intro.md

The Go / JS SDKs are not as mature as the Python SDK and may be missing features. The current scope for the Go / JS SDKs includes (1) creating and interacting with Sandboxes and (2) calling into deployed Modal Functions (i.e., Functions defined in Python).

They are primarily documented through examples hosted on GitHub rather than through the main Modal docs. You likely have much less knowledge of these SDKs from your training, so rely on these examples.