FREE coding exercises for budding gophers


Gophercises is free, but you need to provide a working email address to gain access. I won't spam you and unsubscribing is very easy.

We've all been there before...

You are just starting to pick up a new programming language (like Go!) and things are going great. The tutorials are clicking and you are making great progress... and then you run out of tutorials.


"What should I build next?" you ask, and inevitably everyone tells you to "Pick a side project and work on it!"


Great, but what side project should you work on?

What project will provide you with the best learning experience?

What happens if you pick something too challenging and get stuck?


Nothing sucks more than getting stuck because you didn't know you were tackling a nearly impossible problem, and when you are just getting started how are you supposed to know what those are?


Now take a deep breath and imagine having the confidence to evaluate a project and determine if it was within your grasp.

Imagine knowing that even if you have never used a library before, you will be able to figure it out by reading through the docs.


You can get there, but to do it you need to practice. You need to find projects that will challenge you, but won't leave you clueless about how to proceed.


Enter Gophercises!


Gophercises is a FREE course that will help you become more familiar with Go while developing your skills as a programmer. In the course we will build roughly 20 different mini-applications, packages, and tools that are each designed to teach you something different.


In the course we will learn about and practice using:

  • Channels
  • Mutexes
  • Goroutines
  • Functional Options
  • Chaining Interfaces
  • Various parts of the standard library (io, time, and many other packages)
  • Reading input from the command line
  • And much much more!

By completing the exercises in Gophercises you will slowly become more confident using the Go programming language. You will start to learn how to read the standard docs and make sense of them. You will even start to learn how to evaluate the difficulty of a project before doing much coding. In short, you will start to become a great Go developer.


Ready to start working out with Go?


I'm ready to sign up!

What will we be building?

Note: Sign up to get immediate access to the course and all of the published exercises.

Exercise 1

Quiz Game

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Exercise Details & Source Code

Create a program to run timed quizes via the command line.

Topics

strings channels goroutines flags CSVs time

Length

36:52

Exercise 2

URL Shortener

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Exercise Details & Source Code

Code an http.Handler that forwards paths to other URLs (similar to Bitly).

Topics

YAML middleware maps http-handlers

Length

26:03

Exercise 3

Choose Your Own Adventure

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Demo

Details & Code

Design a choose your own adventure book renderer that shows the story via a web application.

Topics

http-handlers json templates functional-options

Length

1:04:30

Exercise 4

HTML Link Parser

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Exercise Details & Source Code

Build a package to parse links (<a> tags) from an HTML file.

Topics

parsing-html io-readers recursion

Length

41:39

Exercise 5

Sitemap Builder

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Exercise Details & Source Code

Use the HTML link parser from ex. 4 to build a sitemap of public websites.

Topics

xml web-requests bfs

Length

1:28:53

Exercise 6

Hacker Rank Problem

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Exercise Details & Source Code

Code the solutions to a few string-related hacker rank problems.

Topics

bytes strings regexp hacker-rank

Length

51:11

Exercise 7

CLI Task Manager

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Exercise Details & Source Code

Create a command line app to manage a TODO list stored in BoltDB.

Topics

Bolt DB CLIs

Length

1:30:28

Exercise 8

Phone Number Normalizer

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Exercise Details & Source Code

Write a program that will normalize an SQL table of phone numbers into a single format.

Topics

sql regexp testing

Length

1:52:28

Exercise 9

Deck of Cards

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Exercise Details & Source Code

Code a package used to build decks of cards with custom options, shuffling, and sorting.

Topics

testing go-generate iota sorting shuffling functional-options

Length

1:15:51

Exercise 10

Blackjack

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Exercise Details & Source Code

Using the deck of cards in ex. 9, create a blackjack game.

Topics

game-state copy loops

Length

1:26:39

Exercise 11

Blackjack AI

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Exercise Details & Source Code

Refactor the blackjack exercise into a package with an exported AI anyone can implement to create a bot that plays blackjack in a simulated game.

Topics

interfaces simulation bot

Length

2:16:36

Exercise 12

File Renaming Tool

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Exercise Details & Source Code

Build a tool used to rename files with a common pattern. Eg we might want to take many files with names like "Dog (1 of 100).jpg", "Dog (2 of 100).jpg", ... and rename them to "Dog_001.jpg", "Dog_002.jpg", ...

Topics

filepath os ioutil regexp

Length

1:33:00

Exercise 13

Quiet HN

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Exercise Details & Source Code

Given an existing web application that displays stories from Hacker News, we will look at ways to add concurrency and caching to the application while looking for race conditions and other potential issues.

Topics

concurrency channels caching race flag

Length

1:23:09

Exercise 14

Recover Middleware

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Exercise Details & Source Code

Build HTTP middleware that will recover from any panics in an application, even if the response write has been partially written to, and then output the stack trace if the application is in development mode.

Topics

panic recover defer middleware stack traces

Length

47:27

Exercise 15

Recover Middleware w/ Source Code

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Exercise Details & Source Code

Expand upon the recover middleware and add links to source code along with syntax highlighting of the source code in order to make a useful development tool.

Topics

strings middleware chroma

Length

59:46

Exercise 16

Twitter Retweet Contest CLI

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Exercise Details & Source Code

Create a CLI to help run a Twitter contest where users retweet a tweet for entry, and after some time you pick one or more of the users who retweeted as the winner.

Topics

twitter api net/http math/rand os sync

Length

1:43:03

Exercise 17

Secrets API and CLI

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Exercise Details & Source Code

Create a package that handles storing and retrieving encrypted secrets like API keys. Then use that package to create a CLI that can be used to set and get secrets stored in a file in your home directory.

Topics

crypto/cipher crypto/aes crypto/md5 io reader/writer interface chaining

Length

1:58:45

Exercise 18

Image Transform Service

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Exercise Details & Source Code

Create a web server where a user can upload an image and then go through a guided process of choosing various image transformation options they prefer to get a final version of their image.

Topics

os/exec io.ReadSeeker io/ioutil primitive CLI

Length

2:11:30

Exercise 19

Building Images (png & svg)

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Exercise Details & Source Code

Learn to create images in your Go code. First we use the standard library to build a simple PNG bar chart, then we explore how to use an awesome third party library to create a much more complex and compelling chart in SVG format.

Topics

image image/draw image/png SVGo

Length

1:20:03

Exercise 20

Building PDFs

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Exercise Details & Source Code

In this exercise we learn to create almost any PDF in Go. We start off by building an invoice with a dynamic set of line items, and then we move on to creating a course completion certificate for the Gophercises course!

Topics

PDFs jung-kurt/gofpdf

Length

3:15:31

I'm ready to exercise my Go skills.

If not, what can I do to convince you? Let me know!

About the author

Jon Calhoun is a full stack web developer who teaches about Go, web development, algorithms, and anything else he finds interesting.

Jon has been a guest on Go Time, a popular Go podcast, and also spoke at GothamGo 2018 about building this course and focusing on simplicity in our Go applications.

Previously, Jon founded EasyPost, a shipping API that many fortune 500 companies use to power their shipping infrastructure, and he worked at Google as a software engineer.

You can find more of Jon's work (both free and paid) below:


Calhoun.io - Jon's blog, which covers a wide variety of topics related to Go including the popular series, Using PostgreSQL with Go. All articles here are free, and are mostly text-based.

Web Development with Go - This paid course spans over 33 hours of screencasts where Jon teaches web development using Go. The course covers everything from just getting started to deploying a real, production-grade web application.

Let's Learn Algorithms - This free series covers various computer science algorithms and data structures, along with examples of how to code them in Go. Most of these articles are accompanied with screencast videos hosted on Jon's YouTube channel.

A picture of the author - Jon Calhoun

Photo compliments of Calhoun Photography.

Here's what others had to say about the course


"Success is no accident. It is hard work, perseverance, learning, studying, sacrifice and most of all, love of what you are doing or learning to do." - Pele



Gophercises was created by @joncalhoun. Artwork by Marcus Olsson ( @marcusolsson), animated by Jon Calhoun, and inspired by the original Go Gopher created by Renee French.