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Learn Swagger and the OpenAPI Specification (Udemy.com)

API Definition Files, Tools, and Documentation (OAS 2.0)

4.5
6,068 reviews

Created by: Peter Gruenbaum

Last updated January 2026

Our take

Based on the ratings of 6,068 students, a sample of their written reviews and the syllabus, as the course stood in January 2026. No course pays to be reviewed.

Peter Gruenbaum's course is a quick introduction to the OpenAPI Specification, the file format that Swagger tools read. It is written for people who work around APIs rather than build them: project managers, technical writers, technical sales staff. The video part is only about 1.1 hours across 13 lectures. The real work is eight hands-on exercises, which the description says take at least four hours. Topics run from YAML basics to security, documentation and JSON. It teaches OAS 2, not the newer OAS 3.

Reviewers like the teaching. They call Gruenbaum clear and crisp, and one praises his pattern of concept, example, then a chance to try it, adding that he answers questions when students get stuck. One says the class gave them the background they lacked while editing contracts by guesswork. The complaints are consistent, though. Some find it static, with code shown as screenshots instead of typed live. One reviewer could not find the exercise files, and another says Swagger Editor is not introduced until the second assignment. One Spanish-language reviewer calls the videos dated.

With about 33,800 students and roughly 6,000 ratings, mostly four and five stars, the response is steady. It was last updated in January 2026, but the OAS 2 focus will date it for teams already on version 3. Treat it as orientation plus practice, not a deep dive. If your job is to read or write API definitions and you want a fast, low-pressure foundation, it fits well. Developers who want depth should look elsewhere.

Best forTechnical writers, product managers and technical sales staff who need to read or write OpenAPI files but are not developers.
Skip it ifYou need OAS 3, want live coding, or plan to host and customize Swagger on your own server.

Pros

  • Eight step-by-step exercises, ending with a file built from a real commercial API's docs
  • Gruenbaum explains each idea, shows an example, then lets students try it
  • Only about 1.1 hours of video, so it suits people short on time
  • Written for non-developers; one reviewer says it explained contracts they had been editing blind

Cons

  • Teaches OAS 2; OAS 3 gets a single pointer lecture on the differences
  • Code appears as screenshots, so reviewers say it feels static and not like live coding
  • Exercise files are hard to find and Swagger Editor is introduced late, per reviewers
He first introduces concepts, then gives examples, then gives an opportunity to try it out. And he's very responsive if you get stuck and need help.
Alexandra Hart, a student

Labeled intermediate, but it suits non-developers who already understand REST and JSON. No programming is needed.

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What you will learn

  • Read and write Open API Specification (Swagger) files to define and document APIs
  • Use Swagger tools to edit files, create documentation, and create SDKs
  • Understand alternatives to Swagger and OAS.

Course content

3 sections · 13 lectures · 1.1 hours of video 4 quizzes, 8 assignments, 3 articles

  1. 1Introduction 2 free previews3 lectures · 2 quizzes · 19 min
  2. 2Open API Specification5 lectures · 7 quizzes · 35 min
  3. 3Tools and Alternatives5 lectures · 3 quizzes · 11 min

Who it is for

The instructor says it suits

  • Anyone who wants to be able to read or write Open API Specification (Swagger) files
  • Project managers
  • Technical writers
  • Technical sales staff
  • Technically-skilled managers

What you need before you start

  • You should understand how REST APIs work
  • You should be able to read and understand JSON
  • If you need these skills, take my courses on JSON/XML and REST

How it compares

Against the other 1,182 rated Udemy courses in IT & Software on CourseDuck:

  • Rating4.5 out of 5higher than 45% of them
  • Reviews6,068#95 of 1,183 by number of reviews
  • Length1.1 hoursshorter than 95% of them
  • Last updatedJanuary 2026more recently than 62% of them

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Course Description

The OpenAPI Specification (often called "Swagger") is currently the most popular way to create definitions of RESTful APIs. With these definitions, you can create sophisticated, autogenerated documentation, generate SDKs in several languages, and do automated testing. Swagger is a set of open source tools that use these Open API Specification definition files.

This class is for people in the software industry who are fairly technical, but are not software developers: for example, project managers, API product managers, and technical writers. It assumes that you understand REST and JSON, but that's about all. It is meant to be for people who are new to the Open API Specification and Swagger, rather than for experts. It covers:

  • What you can do with OpenAPI Specification (OAS) files

  • The YAML file format

  • How to create an OAS file

  • How to specify security

  • How to add documentation

  • How to write an OAS file in JSON

  • Alternatives to Swagger and OAS

This class does not cover:

  • How to set up Swagger on your own server

  • How to modify Swagger open source code

In addition to videos, this course contains 8 hands-on exercises that lead you step-by-step in creating an API definition file, including a final project where you create a file from scratch using documentation from an actual commercial API. It also contains a document with resources on learning more about OAS, Swagger, and alternatives.

In addition to the video lectures, expect to spend at least 4 hours doing the exercises. These exercises are key to understanding Swagger and OAS.

Important: The course uses OAS 2. A newer version, OAS 3, is starting to be used more, but  many companies are still using OAS 2. There is a lecture that points you to the differences between OAS 2 and OAS 3.
Read More Intermediate Intermediate Level product length iconTime: 1.1h

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Instructor Details

Peter Gruenbaum

Peter founded SDK Bridge to bring together his love of technology and writing. After getting a PhD in solar energy research, he spent 10 years as a software developer and writer. He has worked as an API writer to describe APIs for eCommerce, automobile traffic prediction, electric utilities, mobile phones, and tractors, just to name a few.  He currently works for Calibrant Energy, building software to control solar and wind farms with batteries. Peter received his BA in Physics from the University of Chicago and his PhD in Applied Physics from Stanford University. 

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Reviews

4.5

6,068 ratings on Udemy

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By Shazia Parveen on 9/10/2026

This is a practical and engaging course that provides a solid foundation in OpenAPI and Swagger. The progressive exercises and real-world examples make it effective for beginners, while a few updates to the tooling instructions and advanced concept explanations would make it even stronger.

By Anonymized User on 3/16/2021

This gave a lot of informaiton, but it could flow better. Start with a final page which will show everyone, what you are trying to build. Then slowly build it out in sections. Yes, you did this, but I would have doen the Get, Post, Delete...all together, I would have done all the errors at once. Jumping around and back, made it harder to follow.

By Prasantha Deva on 11/22/2020

Good. Some coverage on how these files used in programming could help.

By Mohan Pavan on 11/15/2020

Thank you for this course. Able to understand and work on OAS.

By PRAVEEN MURTHY on 11/8/2020

no audio in the API definition lecture (section 1, lecture 2)

By Dara M on 11/8/2020

could be updates for OAS 3.0 otherwise great

By Kassie Militello on 10/26/2020

Outdated use Swagger2 annotations and save time

By CONOR KELLY on 10/22/2020

Good course but needs updated to OAS 3.0.

By Tom Ives on 10/19/2020

very complete and comprehensive

By Heather Cloward on 10/18/2020

Good quality information. I especially liked the different YAML syntax explanations.

By Umair Jan Yetoo on 10/16/2020

The explanation is very good. Thank you very much for this course.

By Jay Marley on 10/15/2020

Good information just really boring teaching difficult to sit and listen to

Showing 12 of 221 reviews

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Overall Score : 90 / 100

Learn Swagger and the OpenAPI Specification
Visit course on Udemy Write a review
  • Video Duration: icon 1.1h
  • Price: See price on Udemy
  • Provider: icon Udemy
  • Updated: icon January 2026
  • Level: Intermediate Intermediate
  • Language: icon English
  • Certificate: icon Yes
  • Lectures:13 in 3 sections
  • Practice:4 quizzes
  • Students:33,800
  • Subtitles:9 languages
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