As developers, we spend countless hours integrating third-party services into our applications. When it comes to email APIs, the quality of the SDK can make or break your development experience. A great SDK should feel like a natural extension of your codebase—typed, reliable, and intuitive.
Today, we're putting the major email service SDKs head-to-head to answer one critical question: Who delivers the best SDK developer experience?
Meet the Contenders
Before diving into the technical comparison, let's introduce our contestants:
Nuntly - The Developer-First Platform
A modern email infrastructure designed for developers who value clean, predictable APIs with full type safety, intelligent autocomplete, effortless pagination, and automatic retry logic that just works. While others focus primarily on Node.js, Nuntly's JavaScript SDK works seamlessly across all modern runtimes: Node.js, Deno, Bun, Cloudflare Workers, and Vercel Edge Runtime. This makes it perfect for modern serverless architectures and edge computing.
SendGrid - The Legacy Giant
SendGrid offers scale and enterprise features, but their JavaScript SDK feels dated compared to modern standards. Built in the pre-TypeScript era, it shows its age with loose typing and patterns that feel foreign to developers used to modern tooling.
Mailgun - The Outdated Veteran
Mailgun, sold to Sinch, offers solid email delivery with straightforward APIs, but their Node.js's SDK remains firmly rooted in JavaScript-first patterns that lack the modern TypeScript features developers expect today.
Postmark - The Boring Workhorse
Known for solid deliverability, Postmark lacks official SDKs for popular languages like Go, and the quality varies significantly between their different SDKs. Their approach to modernizing the developer experience feels more retrofitted than built from scratch for modern development.
Resend - The Overhyped Newcomer
A newer player that's gained traction by focusing on developer experience with React-style patterns. Resend offers a decent SDK with a TypeScript support, but it's fairly basic—there's definitely room for improvement. While they've positioned themselves as a modern alternative, their approach feels more like the minimum viable product rather than pushing the boundaries of what's possible for developer experience.
Testing Methodology
We evaluated each SDK across three progressive levels that represent how developers actually assess and adopt new tools. Think of it as the natural progression from "does this work?" to "can I build something amazing with this?"
1. Core Developer Experience
The foundation: Is the API intuitive? Are types comprehensive and helpful? How does error handling work? This covers everything you encounter in daily development—the make-or-break basics that determine if you'll enjoy using the SDK or spend your time fighting it.
2. Advanced Capabilities
The differentiators: Can it handle complex workflows and large datasets? Are there advanced patterns for production use? Does it support modern deployment environments like edge functions? This is where great SDKs separate themselves from merely functional ones.
3. Developer Support
The confidence factor: Is the documentation excellent? Are there practical examples that actually work? Can you get help when you need it? This determines how quickly you can become productive and solve problems when they inevitably arise.

Round 1: Core Developer Experience
You know that feeling when you integrate a new SDK and everything just... clicks? The API makes sense, the types help instead of fighting you, and errors actually tell you what went wrong. That's what separates the great SDKs from the ones that make you want to tear your hair out.
Let's dig into the fundamentals: how these SDKs handle the day-to-day stuff you'll be dealing with constantly—sending emails, working with TypeScript, and debugging when things go sideways.
Nuntly: When Everything Just Works
Here's a basic password reset flow. Nothing fancy, just the kind of code you write every day:
1const nuntly = new Nuntly();
2
3const { data, error } = await client.emails
4  .send({
5    from: 'security@myapp.com',
6    to: 'someone@acme.com',
7    subject: 'Reset your password',
8    html: `
9      <p>Hi John,</p>
10      <p>Click the link below to reset your password:</p>
11      <a href="https://myapp.com/reset/aqwxsz">Reset Password</a>`,
12    tags: [{ name: 'security', value: 'password-reset' }],
13  })
14  .safeAwait();
15
16if (error) {
17  return { success: false, reason: 'email_failed', errorCode: error.status };
18}
19return { success: true, userId: user.id, emailId: data.id };
20

What makes this different:

No try/catch boilerplate – The safeAwait() pattern lets you handle errors cleanly, without cluttering your code with try/catch blocks. Bonus: you can still use try/catch if you prefer.
TypeScript that actually helps - IntelliSense shows you exactly what's available, with descriptions right in your IDE
Errors you can actually use - Structured error types with context, not just "something went wrong"
Sensible defaults - Works out of the box, customize when you need to
Generated from OpenAPI specs – Types are always up-to-date whenever we release new features. This ensures stability for SDKs in any programming language.

The Competition: A Tale of Frustration
Let's see how the same flow looks with other SDKs. Spoiler: it's not pretty.
SendGrid: Fighting the Legacy
SendGrid is one of the oldest email API providers. Let's see how its SDK performs.
1import sgMail from '@sendgrid/mail';
2
3sgMail.setApiKey(process.env.SENDGRID_API_KEY);
4
5try {
6  const msg = {
7    to: 'someone@acme.com',
8    from: 'security@myapp.com',
9    subject: 'Reset your password',
10    html: `<p>Hi John,</p><p>Click the link below...</p>`,
11  };
12
13  const response = await sgMail.send(msg);
14  // Good luck figuring out what this response actually contains
15  return { success: true, emailId: response[0]?.headers?.['x-message-id'] };
16} catch (error: any) {
17  return { success: false, reason: 'email_failed' };
18}
19

What makes SendGrid feel outdated:

Poor TypeScript support – API responses change depending on the operation, making it hard to predict what you'll get back. The response object is basic and not type-safe; response.body is just a raw object with no helpful typings
Limited configuration options – Missing advanced features like custom logging and fetch overrides
Manual error handling – Stuck with old-school try/catch patterns and manual error parsing, which slows development and increases bug risk
Split SDK – The SendGrid SDK is divided into multiple packages (e.g., @sendgrid/mail, @sendgrid/client, etc.), which can be confusing for new users. You may need to install and import several packages to access all features, making setup and maintenance more complex.

Mailgun: The Old-School Approach
Now let's see how Mailgun handles the same code.
1import formData from 'form-data';
2import Mailgun from 'mailgun.js';
3
4const mailgun = new Mailgun(formData);
5const mg = mailgun.client({ username: 'api', key: process.env.MAILGUN_API_KEY });
6
7try {
8  const response = await mg.messages.create('myapp.com', {
9    from: 'security@myapp.com',
10    to: 'someone@acme.com',
11    subject: 'Reset your password',
12    html: `<p>Hi John,</p><p>Click the link below...</p>`,
13    'o:tag': 'reset', // This field name tells you everything about its age
14  });
15
16  return { success: true, emailId: response.id };
17} catch (error: any) {
18  // Minimal error context, mostly just string messages
19  return { success: false, reason: 'email_failed' };
20}
21

What makes Mailgun feel outdated:

Unusual constructor pattern – Requires formData import and complex client setup that feels foreign to modern JavaScript
Late TypeScript adoption – Support was added as an afterthought and originally required external packages for the types
Legacy field naming – The 'o:tag' field reflects older system conventions instead of modern camelCase
No modern error patterns – Stuck with traditional try/catch, no safeAwait-style alternatives
Minimal error context – Response status is just a number, not intuitive for debugging or error handling
Community workarounds needed – The community created ts-mailgun to address limited TypeScript support

Postmark: Almost There
Let's see how Postmark handles sending an email with its SDK.
1import { ServerClient } from 'postmark';
2
3const client = new ServerClient(process.env.POSTMARK_API_TOKEN);
4
5try {
6  const response = await client.sendEmail({
7    From: 'security@myapp.com', // PascalCase feels weird in JS land
8    To: 'someone@acme.com',
9    Subject: 'Reset your password',
10    HtmlBody: `<p>Hi John,</p><p>Click the link below...</p>`,
11  });
12
13  return { success: true, emailId: response.MessageID };
14} catch (error: any) {
15  return { success: false, reason: 'email_failed' };
16}
17

What makes Postmark feel inconsistent:

PascalCase property names – Uses 'From', 'To', 'Subject', 'HtmlBody' instead of modern JavaScript camelCase conventions
JavaScript-first approach – Official SDK is primarily written in JavaScript, making TypeScript integration less seamless
Stale development – Last release was in June 2024, raising concerns about ongoing development after ActiveCampaign acquisition
Beta features in production – Essential features like batch email sending are still marked as Work in progress and limited to early access customers
Inconsistent developer experience – Mix of modern and legacy patterns throughout the SDK

Resend: The Overhyped Newcomer
And finally, Resend, the newest competitor, will show us how the latest entrant performs.
1import { Resend } from 'resend';
2
3const resend = new Resend(process.env.RESEND_API_KEY);
4
5try {
6  const { data } = await resend.emails.send({
7    from: 'security@myapp.com',
8    to: 'someone@acme.com',
9    subject: 'Reset your password',
10    html: `<p>Hi John,</p><p>Click the link below...</p>`,
11  });
12
13  return { success: true, emailId: data?.id };
14} catch (error: any) {
15  return { success: false, reason: 'email_failed' };
16}
17

What makes Resend overhyped:

React dependency bloat – Includes React as a dependency, causing issues for Express.js and other non-React projects, a frequent complaint about unnecessary bloat for server-side usage
Fundamentally broken TypeScript experience – Response structure was inconsistent for a long time, developers waited over a year for proper return types and had to create their own type definitions or add extra boilerplate just to handle basic error handling
The SDK, much like the API itself, is missing essential features that developers expect, such as listing sent emails or checking the status of batch email operations, making it harder to build robust email workflows
Scattered examples – Example code is spread across multiple repositories, making it harder for developers to quickly find relevant, working code. This can slow down onboarding and troubleshooting, especially when trying to implement specific features.

The Winner: Nuntly
When it comes to core developer experience, Nuntly is the clear winner. Its clean API, truly helpful TypeScript support, and practical error handling make development smooth and frustration-free. Unlike competitors stuck with legacy patterns or bolted-on TypeScript, Nuntly is built from the ground up for modern JavaScript and TypeScript workflows, so everything just works, right out of the box.

Round 2: Advanced Capabilities
Okay, so the basics work. But here's where things get interesting. Modern applications aren't just sending simple emails anymore, you're dealing with massive datasets requiring pagination, production environments that need to be reliable every time, raw response access for debugging, and edge functions across different runtimes.
This is where most SDKs show their age. They were built for a simpler world and haven't kept up with how we actually build software today. You also see basic MVP SDKs that are essentially just HTTP wrappers, they might send an email, but they lack the sophisticated features developers need for real applications.
Pagination: Iterate Through Items
Here's a scenario you've probably faced: you need to export all your email data, or analyze delivery patterns, or migrate to a new system. As developers, we know pagination can be a pain: managing cursors, handling edge cases, and writing boilerplate just to get all your data.
Let's see how Nuntly handles this scenario, and how the competition stacks up.
Nuntly makes it effortless
1// This just works - no cursor management, no manual loops
2async function exportAllEmails() {
3  const emails = [];
4
5  for await (const email of client.emails.list()) {
6    emails.push({
7      id: email.id,
8      subject: email.subject,
9      status: email.status,
10      sentAt: email.sentAt,
11      opens: email.openCount,
12    });
13  }
14
15  return emails;
16}
17
18// Need more control? Manual pagination is there too
19let page = await client.emails.list();
20while (page.hasNextPage()) {
21  // Process current page
22  await processEmails(page.data);
23  // Get next page
24  page = await page.getNextPage();
25}
26

What makes Nuntly's pagination different:

Built-in auto-pagination – Use for await...of to process large datasets without worrying about cursors or page tokens
Type-safe iteration – Every paginated item is fully typed
Zero boilerplate – No cursor management or edge case handling required
Keep control when needed – Full pagination control available for complex scenarios

The competitors: Manual and Messy

SendGrid: Manual pagination only, classic offset/limit system, no built-in helpers to make developers' lives easier. Pagination info is exposed in response headers, good luck if you want to manage yourself
Mailgun: Some methods support pagination, but not all. The pagination response structure is complex, with separate blocks for first, last, next, and previous pages. There are no built-in helpers for easy iteration—you have to manage pagination manually.
Postmark: Documentation is weak on pagination. Filtering is supported, but there’s no easy way to iterate over results, its returns only the total count, so you have to handle all pagination logic manually.
Resend: No auto-pagination support at all.

Production-Ready Advanced Configuration
When you're running in production, you need real control: custom timeouts for critical emails, advanced logging for debugging, and even customization for fetch to fit your needs.
Email delivery is inherently unreliable—networks fail, services hiccup, and rate limits kick in. Most SDKs leave you to build your own retry logic. Nuntly handles all this complexity for you, so your emails get delivered reliably, even in tough conditions.
Let's see how these SDKs perform in real-world, high-pressure scenarios.
Nuntly: Built for Reliability
Nuntly’s configuration is straightforward and developer-friendly. You get sensible defaults out of the box, but can easily customize for production.
1// Production configuration
2const nuntly = new Nuntly({
3  apiKey: process.env.NUNTLY_API_KEY,
4  baseURL: process.env.NUNTLY_BASE_URL,
5  timeout: 5_000,
6  maxRetries: 2,
7  logLevel: 'debug',
8  logger: structuredLogger.child({ service: 'email' }),
9  fetch: customFetch,
10});
11
12// Per-request overrides for special cases
13await nuntly.emails.send(
14  { ... },
15  {
16    timeout: 8_000, // Give this one extra time
17    maxRetries: 3, // Make sure it gets through
18  }
19);
20

What makes Nuntly's built-in reliability features stand out:

Fine-grained control: Customize timeouts, retries, and logging globally
Flexible per-request overrides: Adjust behavior for critical workflows without changing your global setup.
Automatic retries for transient failures with exponential backoff
Request tracing with unique IDs for debugging
Custom fetch support: Easily swap in your own fetch implementation for edge, proxy, or testing environments.
Type-safe configuration: All options are clearly typed, so you always know what’s available.

The competitors: Limited
Most SDKs give you basic configuration and call it a day.

SendGrid: Basic configuration options, but lacks advanced features like per-request overrides and custom fetch support. Timeouts are global only, no way to adjust for specific requests.
Mailgun: Global timeout only, no retry mechanisms, no built-in logging support, and no way to customize fetch behavior. The proxy configuration is also quite rigid compared to Nuntly that give you the full control on fetch configuration.
Postmark: global timeout configuration, no advanced logging or retry options. Timeouts are fixed and not customizable per request.
Resend: No advanced configuration options, and lacks built-in logging or retry mechanisms.

Raw Response Access: When You Need Everything
Sometimes you need more than just the parsed response, you need to access to the raw response for implementing custom logic, or debugging a tricky issue or anything else you want.
Nuntly offers full access
Nuntly gives you access to everything:
1// Get the raw HTTP response
2const response = await client.emails.send({ ... }).asResponse();
3
4console.log('Rate limit remaining:', response.headers.get('RateLimit-Remaining'));
5console.log('Request ID for support:', response.headers.get('Request-Id'));
6
7// Or get both parsed data and raw response
8const { data, response: raw } = await client.emails.send(emailData).withResponse();
9
10// Log everything for debugging
11logger.info('Email sent', {
12  emailId: data.id,
13  requestId: raw.headers.get('X-Request-ID'),
14  rateLimitRemaining: raw.headers.get('X-RateLimit-Remaining'),
15  responseTime: raw.headers.get('X-Response-Time'),
16});
17

What makes Nuntly's raw response access unique:

Comprehensive data: Get all headers and metadata without any extra work.
Debugging made easy: Log raw responses alongside parsed data for quick issue resolution.
Custom logic: Implement advanced workflows that depend on raw response details.

The competitors
SendGrid: Surprisingly, while the SDK does not provide type-safe response objects, you do have access to the raw response. However, headers are typed as "any" and the body is just a plain object, making it difficult to write safe, reliable code. You'll need to manually parse and validate everything yourself.
Mailgun: No built-in way to access the raw HTTP response. You only get the parsed data, so if you need headers or low-level details for debugging or advanced workflows, you're out of luck.
Postmark: Only returns the parsed JSON body, not the raw HTTP response. If you need access to the HTTP status or headers, you'll have to implement it yourself.
Resend: No support for accessing the raw HTTP response. If you need headers or low-level details, you'll have to fork the SDK and implement it yourself. This limits flexibility and makes debugging or advanced workflows much harder for developers.
Edge Runtime Support: The Modern Reality
If you're building anything modern, you're probably deploying to edge functions, serverless environments, or at least thinking about it. Here's the thing: most email SDKs were built for traditional Node.js servers and struggle with these new environments.
Nuntly? It just works, everywhere:
The following runtimes are supported:

✅ Node.js - Obviously
✅ Deno - First-class support
✅ Bun - Lightning fast
✅ Cloudflare Workers - Edge computing
✅ Vercel Edge Runtime - Global deployment
✅ Web browsers - Up-to-date Chrome, Firefox, Safari, Edge, and more
✅ Jest, Nitro, ..

The competitors: Falling Behind
Meanwhile, the competitors are stuck, still catching up:

SendGrid: Built for the pre-serverless world, no support for Edge Runtime. The SDK relies on Node.js-specific APIs and third party librairies like axios, making it incompatible with edge environments. Developers have reported issues when trying to use it in Cloudflare Workers or Vercel Edge.
Mailgun: It is a Node.js only SDK, no support for Edge Runtime. The SDK is built on top of Node.js and does not account for the unique constraints of edge environments. Developers have encountered issues to use fetch by themselves.
Postmark: Does not support Edge Runtime. Developers have reported issues for years without a successful resolution, except to implement it yourself. As a result, the community has created a fork to add Edge Runtime support.
Resend: Good support for Edge runtime like Cloudflare Workers and Vercel Edge, as well as Bun and Deno. No mention if this SDK supports Browsers.

The Winner: Nuntly
When you need to build something that works reliably in production, across different environments, with real-world data volumes, Nuntly gives you the tools that others SDKs just don't have.

Round 3: Developer Support
Great documentation is the backbone of developer experience. It's not just about getting started. It's about confidence. When you're building something important, you need to know that the SDK you're depending on is well-supported, well-documented, and that help is available when you need it.
In this round, we compare how each provider supports developers with guides, examples.
Nuntly: Documentation That Actually Helps
Nuntly's documentation stands out with its modern, visually appealing design, interactive playground, and examples. The developer-first approach means onboarding is lightning-fast, dark mode is available, and guides are clear, technical, and free of fluff. A git hub repository includes a wide range of practical examples for nearly every endpoint—not just basic email sending, so you can quickly find code that matches your needs. See the full set of examples here: Nuntly SDK Examples.
The Competition: A Mixed Bag
SendGrid: Overwhelming but Outdated
SendGrid has the most comprehensive documentation, sometimes too comprehensive. You'll find detailed examples for dozens of languages and exhaustive troubleshooting guides. The problem? Much of it feels outdated, navigation is confusing, multiple docs version, and hard to search.
Mailgun: Functional but Dated
Mailgun's docs are straightforward and technical—lots of cURL examples that make the API easy to understand. They provide Postman collections for quick testing, and a good webhook documentation. But the UI/UX feels like it's from 2015, the search is poor and SDK example quality varies by language.
Postmark: Solid but Boring
Postmark has well-organized documentation with a logical structure and practical examples that actually work. You'll find good deliverability advice and useful debugging guides.
The design is functional, lot of cURL examples along the API reference and there's a Swagger like interactive playground. It gets the job done but doesn't make the experience enjoyable.
Resend: Pretty
Resend offers beautiful, modern documentation with an interactive playground and sleek design. The examples are clean and easy to follow. However, the documentation structure can feel overwhelming, as there are many pages for different frameworks and technologies, making it harder to quickly find what you need.
However, example code is scattered across multiple repositories depending on the tech stack, which can be confusing. For instance, the official Node.js example repository (https://github.com/resend/resend-node-example) contains only a single example!
The Winner: Nuntly
Nuntly wins this round because it treats documentation as a first-class feature, not an afterthought. Its documentation is truly built for developers. The interactive playground lets you test code instantly, and the SDK repo includes examples by endpoint, so you’re never left searching for answers. Compared to competitors, Nuntly’s docs save you time and frustration, letting you focus on building.
Quick Wrap-Up
This comparison was designed to be practical: we tested each SDK on the points that matter most for code developer experience, advanced capabilities, and developer support. The goal: help you choose quickly, without marketing fluff.
Here’s the summary table for all criteria:
The Final Scorecard
Criteria
Nuntly
SendGrid
Mailgun
Postmark
Resend
Core Developer Experience
⭐⭐⭐⭐⭐
⭐
⭐⭐
⭐⭐⭐⭐
⭐⭐⭐
Advanced Capabilities
⭐⭐⭐⭐⭐
⭐⭐
⭐⭐
⭐⭐
⭐⭐
Developer Support
⭐⭐⭐⭐⭐
⭐⭐⭐
⭐⭐⭐
⭐⭐⭐⭐
⭐⭐⭐⭐
Overall
🏆 Winner
Legacy
Outdated
Boring
Overhyped

The Verdict: Nuntly Wins!
When it comes to developer experience, type safety, and modern development practices, Nuntly's SDK doesn't just lead—it dominates. While established players like SendGrid and Mailgun rest on their legacy, Nuntly delivers what developers actually want in 2025.
Why Developers Choose Nuntly:

🏆 Best-in-class TypeScript Support
⚡ Modern Development Patterns
🛡️ Production-Ready Reliability
📖 Developer Experience That Just Works


Don't get stuck in 2010, your emails deserve better SDKs!
🎯 Start free Now →

✅ No credit card required
✅ 10,000 free emails
✅ Full SDK access
✅ Fastest onboarding

Join thousands of developers who've already made the switch. Your future self will thank you.
Questions? Tweet us @nuntly_com or join our developer Discord for instant support.