I see a public API without an SDK and think: that company doesn't understand developer experience. But it's worse. It's not apathy. It's tactical incompetence. Because the solution exists. And they chose not to use it.

Incompetence is optional

In 2025, not having an SDK isn't a technical problem. It's a public admission that your team doesn't know, can't, or doesn't care.

Multiple tools exist that generate SDKs automatically from a good API spec. You don't need to write code. You just need an honest OpenAPI spec.

// If you have an OpenAPI spec (you should)
{
  "openapi": "3.0.0",
  "info": { "title": "My API", "version": "1.0.0" },
  "paths": {
    "/emails": {
      "post": {
        "requestBody": {
          "required": true,
          "content": {
            "application/json": {
              "schema": {
                "type": "object",
                "properties": {
                  "from": { "type": "string" },
                  "to": { "type": "array", "items": { "type": "string" } },
                  "subject": { "type": "string" },
                  "html": { "type": "string" }
                },
                "required": ["from", "to", "subject", "html"]
              }
            }
          }
        }
      }
    }
  }
}

You have that. You have this option:

// Option 1: hey-api/openapi-ts (minimal)
npx @hey-api/openapi-ts --input ./openapi.json --output ./sdk

// Option 2: Speakeasy (professional, more features)
speakeasy generate sdk --schema ./openapi.json

// Option 3: openapi-generator (maximum control)
openapi-generator-cli generate -i openapi.json -g typescript -o ./sdk

// SDK is done. Zero lines of code written by hand. Zero maintenance.
// Always in sync with your API.

// Integrate into CI/CD:
// - GitHub Actions: Run generation on every spec change
// - Publish to npm automatically
// - Validate SDK against live API in test environment
// - Version bumps happen automatically

Your SDK is done. Zero lines of code written by hand. Zero maintenance. Always in sync with your API. Integrated into CI/CD—the SDK regenerates and publishes automatically every time your spec changes. Your developers never touch it.

If your company uses curl in the documentation, you're telling your market: "We don't know the tools that exist".

The invisible cost without SDK

When a company publishes an API and only offers curl documentation, they're delegating work. Not to specialists. To everyone. To every one of their developer users.

curl -X POST 'https://api.example.com/emails' \
     -H 'Authorization: Bearer xxx_token_xxx' \
     -H 'Content-Type: application/json' \
     -d $'{
  "from": "company@example.com",
  "to": ["user@example.com"],
  "subject": "hello world",
  "html": "<p>it works!</p>",
  "reply_to": "support@example.com"
}'

That example is where most companies think their responsibility ends. In reality, that's where the real problem begins.

Every developer reinvents the wheel

Without an SDK, every team integrating your API writes the same code. Not the logic. The boilerplate. Fetch, headers, error handling, validation.

// Developer has to write this
const sendEmail = async (email: string, subject: string) => {
  try {
    const response = await fetch('https://api.example.com/emails', {
      method: 'POST',
      headers: {
        'Authorization': `Bearer ${process.env.API_KEY}`,
        'Content-Type': 'application/json',
      },
      body: JSON.stringify({
        from: 'company@example.com',
        to: [email],
        subject: subject,
        html: '<p>Hello</p>',
        reply_to: 'support@example.com'
      })
    })

    if (!response.ok) {
      throw new Error(`Error: ${response.status}`)
    }

    return response.json()
  } catch (error) {
    console.error('Email failed:', error)
    throw error
  }
}

Multiply that by 500 teams. 500 implementations of the same integration. 500 versions of the truth. Some handle errors. Others don't. Some validate. Others don't.

If you're the company, this is your problem. Each of those 500 teams asks questions in your Slack. Each one reports different bugs. Each one questions why certain fields don't work as expected.

All of that is support you could have avoided with an automatically generated SDK.

The SDK is the control center

A well-built SDK is the canonical version. The only place where integrating your API correctly matters. Developers don't think. They write.

// With SDK, developer does this
import { Client } from '@mycompany/sdk'

const client = new Client(process.env.API_KEY)

const sendEmail = async (email: string, subject: string) => {
  return client.emails.send({
    from: 'company@example.com',
    to: [email],
    subject: subject,
    html: '<p>Hello</p>',
    reply_to: 'support@example.com'
  })
}

With that SDK, I solve every problem once:

1. Error handling. Not each developer. Me. One implementation. Versioned. Maintained.

2. Type safety. No confusion about which fields are required, which types they accept, or what the correct order is.

// Without SDK: types are a guess
const data = {
  from: 'company@example.com',
  to: [email],
  // Is it email or to? subject or subj? Check the docs...
  subject: subject,
  html: content,
  reply_to: 'support@example.com'
}

// With SDK: types are automatic, always synced
import type { EmailRequest } from '@mycompany/sdk'

const data: EmailRequest = {
  from: 'company@example.com',
  to: [email],
  subject: subject,
  html: content,
  reply_to: 'support@example.com'
}

3. Retries and resilience. Rate limiting handled. Exponential backoff automatic. Resilience by default.

// Without SDK: every developer reimplements retries
const sendEmailWithRetry = async (email: string, attempt = 0): Promise<any> => {
  try {
    return await fetch('https://api.example.com/emails', {
      method: 'POST',
      headers: { 'Authorization': `Bearer ${process.env.API_KEY}` },
      body: JSON.stringify({ to: email })
    })
  } catch (error) {
    if (attempt < 3) {
      await new Promise(r => setTimeout(r, 1000 * Math.pow(2, attempt)))
      return sendEmailWithRetry(email, attempt + 1)
    }
    throw error
  }
}

// With SDK: it's built-in
const client = new Client(process.env.API_KEY)
await client.emails.send({ to: email }) // automatic retries

4. Guaranteed synchronization. The SDK regenerates from your OpenAPI spec. Never drift. Never surprises.

The moment of truth: buyer decision

A developer faces a choice. They need a service. They compare two options:

// Real-world buyer decision scenario

// API without SDK
const emailService = fetch('https://api-no-sdk.com/send', {
  // 30 minutes of setup
  // Manual headers
  // Manual error handling
  // No types
  // No type documentation
})

// Alternative API WITH SDK
import { EmailService } from '@api-with-sdk/sdk'
const emailService = new EmailService(process.env.API_KEY)
// 2 minutes of setup
// Everything typed
// IntelliSense works
// Documentation embedded in code

At a technical level, both APIs could be identical. The difference is here.

Without SDK: 30 minutes of setup. Boilerplate. Manual testing. Risk of errors.

With SDK: 2 minutes of setup. Everything typed. IntelliSense works. Documentation in the code.

In a real decision, the developer chooses the alternative with SDK. Not because it's better technically. But because it's easier. And it's your job to make it easy.

If you don't, you lose that customer to a competitor. And you never even know why.

This affects real adoption

It's not a detail. It's a metric. Companies with SDKs have:

• Faster adoption. Less friction on first use.

• Less support overhead. The SDK is living documentation. Fewer dumb questions.

• Better user experience. The developer feels you care.

• Informed decisions. You know exactly how your API is used. Real adoption metrics.

Without an SDK, you lose all of that. And every new user is a mystery. Are they using your API correctly? Without errors? Respecting limits? You don't know. Each integrator can do whatever they want.

The message you send

When you publish your API with just curl, the message is clear:

"We care that it exists. We don't care that it's easy".

An SDK says the opposite:

"We care about your time. We care that you integrate quickly. We solved the boring problems for you".

In a saturated market of options, that message determines whether developers recommend you or avoid you.

It's not a resource issue. It's a priority issue.

Many companies without SDKs say: "We don't have bandwidth to maintain an SDK".

False. If you have an OpenAPI spec and use hey-api, Speakeasy, or openapi-generator, you don't maintain anything. The SDK generates automatically.

The truth is harsher: you didn't prioritize it. You didn't believe it mattered. And that's what your users read.

The closing

No SDK isn't an engineering problem. It's a vision problem. It says: "My users matter enough that I make things easy." Or not.

If your company has a public API without an SDK in 2025, you're a losing company. Not from lack of money. From lack of judgment.

The tools exist. The practices exist. The cost is near zero. If you don't have an SDK, you chose not to.

And that's what the market reads.