resend / resend-cli

Resend CLI The official CLI for Resend. Built for humans, AI agents, and CI/CD pipelines. Install cURL Node.js Homebrew (macOS / Linux) PowerShell (Windows) Or download the directly from the GitHub releases page. Local development Use this when you want to change the CLI and run your build locally. Prerequisites • Node.js 20+ Setup • **Clone the repo** • **Install dependencies** • **Build locally** Output: Running the CLI locally Use the dev script: Or run the built JS bundle: Making changes After editing source files, rebuild: Building native binaries To build a standalone native binary: Output: Quick start --- Authentication The CLI resolves your API key using the following priority chain: | Priority | Source | How to set | |----------|--------|------------| | 1 (highest) | flag | | | 2 | env var | | | 3 (lowest) | Config file | | If no key is found from any source, the CLI errors with code . --- Commands Authenticate by storing your API key locally. The key is validated against the Resend API before being saved. Interactive mode (default in terminals) When run in a terminal, the command checks for an existing key: • **No key found** — Offers to open the Resend API keys dashboard in your browser so you can create one, then prompts for the key. • **Existing key found** — Shows the key source ( , ) and prompts for a new key to replace it. The key is entered via a masked password input and must start with . Non-interactive mode (CI, pipes, scripts) When stdin is not a TTY, the flag is required: Omitting in non-interactive mode exits with error code . Options | Flag | Description | |------|-------------| | | API key to store (required in non-interactive mode) | Output On success, credentials are saved to with permissions (owner read/write only). The config directory is created with permissions. Error codes | Code | Cause | |------|-------| | | No provided in non-interactive mode | | | Key does not start with | | | Resend API rejected the key | Switch between teams and accounts If you work across multiple Resend teams or accounts, the CLI handles that too. Switch between profiles without logging in and out: You can also use the global (or ) flag on any command to run it with a specific profile. --- Send an email via the Resend API. Provide all options via flags for scripting, or let the CLI prompt interactively for missing fields. Options | Flag | Required | Description | |------|----------|-------------| | | Yes | Sender email address (must be from a verified domain) | | | Yes | One or more recipient email addresses (space-separated) | | | Yes | Email subject line | | | One of text/html/html-file | Plain text body | | | One of text/html/html-file | HTML body as a string | | | One of text/html/html-file | Path to an HTML file to use as body | | | No | CC recipients (space-separated) | | | No | BCC recipients (space-separated) | | | No | Reply-to email address | Interactive mode When run in a terminal without all required flags, the CLI prompts for missing fields: Non-interactive mode When piped or run in CI, all required flags must be provided. Missing flags cause an error listing what's needed: A body ( , , or ) is also required — omitting all three exits with code . Examples **Multiple recipients:** **HTML from a file:** **With CC, BCC, and reply-to:** **Overriding the API key for one send:** Output Returns the email ID on success: Error codes | Code | Cause | |------|-------| | | No API key found or client creation failed | | | No , , or provided | | | Could not read the file passed to | | | Resend API returned an error | --- Run environment diagnostics. Verifies your CLI version, API key, domains, and detects AI agent integrations. Checks performed | Check | Pass | Warn | Fail | |-------|------|------|------| | **CLI Version** | Running latest | Update available or registry unreachable | — | | **API Key** | Key found (shows masked key + source) | — | No key found | | **Domains** | Verified domains exist | No domains or all pending verification | API key invalid | | **AI Agents** | Lists detected agents (or none) | — | — | The API key is always masked in output (e.g. ). Interactive mode In a terminal, shows animated spinners for each check with colored status icons: JSON mode Each check has a of , , or . The top-level is if any check is . Detected AI agents | Agent | Detection method | |-------|-----------------| | OpenClaw | directory exists | | Cursor | directory exists | | Claude Desktop | Platform-specific config file exists | | VS Code | in current directory | Exit code Exits when all checks pass or warn. Exits if any check fails. --- Global options These flags work on every command and are passed before the subcommand: | Flag | Description | |------|-------------| | | Override API key for this invocation (takes highest priority) | | | Profile to use (overrides env var) | | | Force JSON output even in interactive terminals | | | Suppress spinners and status output (implies ) | | | Print version and exit | | | Show help text | --- Output behavior The CLI has two output modes: | Mode | When | Stdout | Stderr | |------|------|--------|--------| | **Interactive** | Terminal (TTY) | Formatted text | Spinners, prompts | | **Machine** | Piped, CI, or | JSON | Nothing | Switching is automatic — pipe to another command and JSON output activates: Error output Errors always exit with code and output structured JSON to stdout: --- Agent & CI/CD usage CI/CD Set as an environment variable — no needed: AI agents Agents calling the CLI as a subprocess automatically get JSON output (non-TTY detection). The contract: • **Input:** All required flags must be provided (no interactive prompts) • **Output:** JSON to stdout, nothing to stderr • **Exit code:** success, error • **Errors:** Always include and fields --- Configuration | Item | Path | Notes | |------|------|-------| | Config directory | | Respects…