OpenAI publishes an official command-line tool for its API

OpenAI published openai-cli on GitHub, which it calls the official CLI for the OpenAI REST API. It is written in Go (1.26 or later to build from source), licensed under Apache 2.0, and installs with brew install openai/tools/openai or go install. Pull requests are limited to repository collaborators.

According to its README:

• Commands follow openai <resource> [subresource...] <command>, for example openai responses create --input "Say this is a test" --model gpt-5.5. Standard endpoints use OPENAI_API_KEY; admin endpoints such as organization usage use OPENAI_ADMIN_KEY.
• JSON responses print as readable text by default; --format json or jsonl gives machine-readable output, and --transform extracts fields with GJSON syntax.
• openai images generate saves images to ~/Downloads/gpt-images/ and uses gpt-image-2.5-sunburst by default. images create-variation is retired; use images edit with a GPT Image model instead.
• It supports mutual TLS (a beta program), custom headers, a --base-url override, and an untrusted-stdin mode that stops @file references in piped input from reading local files.
• A bare openai checks for newer releases at most once every seven days; OPENAI_CLI_NO_UPDATE_CHECK=1 turns that off.
• The first eligible interactive run saves image-picker Tab shortcuts for Bash, zsh and fish.