# Resend SDK Installation Guide

Always install the latest SDK version to ensure you have support for all features including webhook verification (`webhooks.verify()`) and email receiving (`emails.receiving.get()`). Older versions may not include these methods.

## Minimum SDK Versions

These are the minimum versions required for full functionality (sending, receiving, and webhook verification). Always prefer the latest version when possible.

| Language | Package | Min Version | Install |
|----------|---------|-------------|---------|
| Node.js | `resend` | >= 6.9.2 | `npm install resend` |
| Python | `resend` | >= 2.21.0 | `pip install resend` |
| Go | `resend-go/v3` | >= 3.1.0 | `go get github.com/resend/resend-go/v3` |
| Ruby | `resend` | >= 1.0.0 | `gem install resend` |
| PHP | `resend/resend-php` | >= 1.1.0 | `composer require resend/resend-php` |
| Rust | `resend-rs` | >= 0.20.0 | `cargo add resend-rs` |
| Java | `resend-java` | >= 4.11.0 | See [Maven/Gradle](#java) below |
| .NET | `Resend` | >= 0.2.1 | `dotnet add package Resend` |

> **If the project already has a Resend SDK installed**, check the version and upgrade if it's below the minimum. Older SDKs may be missing `webhooks.verify()` or `emails.receiving.get()`, which are required for inbound email and webhook security.

## Detecting Project Language

Check for these files to determine the project's language/framework:

| File | Language | SDK |
|------|----------|-----|
| `package.json` | Node.js/TypeScript | resend |
| `requirements.txt` or `pyproject.toml` | Python | resend |
| `go.mod` | Go | resend-go/v3 |
| `Gemfile` | Ruby | resend |
| `composer.json` | PHP | resend/resend-php |
| `Cargo.toml` | Rust | resend-rs |
| `pom.xml` or `build.gradle` | Java | resend-java |
| `*.csproj` or `*.sln` | .NET | Resend |
| `mix.exs` | Elixir | resend |

## Installation Commands

### Node.js

```bash
npm install resend
```

Alternative package managers:
```bash
yarn add resend
pnpm add resend
bun add resend
```

### Python

```bash
pip install resend
```

### Go

```bash
go get github.com/resend/resend-go/v3
```

### Ruby

```bash
gem install resend
```

Or add to Gemfile:
```ruby
gem 'resend'
```

### PHP

```bash
composer require resend/resend-php
```

### Rust

```bash
cargo add resend-rs
cargo add tokio -F macros,rt-multi-thread
```

### Java

Gradle:
```gradle
implementation 'com.resend:resend-java:4.11.0'
```

Maven:
```xml
<dependency>
  <groupId>com.resend</groupId>
  <artifactId>resend-java</artifactId>
  <version>4.11.0</version>
</dependency>
```

### .NET

```bash
dotnet add package Resend
```

### Elixir

Add to `mix.exs`:
```elixir
def deps do
  [
    {:resend, "~> 0.4.0"}
  ]
end
```

## API Key Setup

All SDKs require a Resend API key. Get one at https://resend.com/api-keys

Recommended: Store API key in environment variable `RESEND_API_KEY` rather than hardcoding.

## cURL (No SDK)

For quick tests or languages without an SDK, use the REST API directly:

```bash
curl -X POST 'https://api.resend.com/emails' \
  -H 'Authorization: Bearer re_xxxxxxxxx' \
  -H 'Content-Type: application/json' \
  -d '{
    "from": "Acme <onboarding@resend.dev>",
    "to": ["delivered@resend.dev"],
    "subject": "hello world",
    "html": "<p>it works!</p>"
  }'
```