Loading...

CodeCrafters

Catalog Badges Vote

Master TypeScript.

TypeScript mastery exercises. Become your team's resident TypeScript expert.

TypeScript

Build your own grep

Build your own grep

Learn about regular expressions and how they're evaluated. Implement your own version of grep in TypeScript.

Match a literal character

Match alphanumeric characters

Positive Character Groups

Negative Character Groups

Combining Character Classes

Start of string anchor

End of string anchor

Match one or more times

Match zero or one times

Backreferences

Single Backreference

Multiple Backreferences

Nested Backreferences

Build your own HTTP server

Build your own HTTP server

HTTP is the protocol that powers the web. In this challenge, you'll build a HTTP server that's capable of handling simple GET/POST requests, serving files and handling multiple concurrent connections.

Along the way, we'll learn about TCP connections, HTTP headers, HTTP verbs, handling multiple connections and more.

Respond with 200

Extract URL path

Respond with body

Concurrent connections

Read request body

HTTP Compression

Compression headers

Multiple compression schemes

Gzip compression

Build your own Redis

Build your own Redis

Discover concurrent programming in TypeScript while also learning about TCP servers, network programming, and the Redis Protocol.

Respond to PING

Respond to multiple PINGs

Handle concurrent clients

Implement the ECHO command

Implement the SET & GET commands

RDB Persistence

RDB file config

Read a string value

Read multiple keys

Read multiple string values

Read value with expiry

Replication

Configure listening port

The INFO command

The INFO command on a replica

Initial Replication ID and Offset

Send handshake (1/3)

Send handshake (2/3)

Send handshake (3/3)

Receive handshake (1/2)

Receive handshake (2/2)

Empty RDB Transfer

Single-replica propagation

Multi Replica Command Propagation

Command Processing

ACKs with no commands

ACKs with commands

WAIT with no replicas

WAIT with no commands

WAIT with multiple commands

Streams

The TYPE command

Create a stream

Validating entry IDs

Partially auto-generated IDs

Fully auto-generated IDs

Query entries from stream

Query single stream using XREAD

Query multiple streams using XREAD

Blocking reads without timeout

Blocking reads using $

Transactions

The INCR command (1/3)

The INCR command (2/3)

The INCR command (3/3)

The MULTI command

The EXEC command

Empty transaction

Queueing commands

Executing a transaction

The DISCARD command

Failures within transactions

Multiple transactions

Build your own Git

Build your own Git

Dive into the internals of Git. Discover how Git stores and moves around data, its transfer protocols, and more. A unique exercise in making network requests with TypeScript.

Initialize the .git directory

Read a blob object

Create a blob object

Read a tree object

Write a tree object

Create a commit

Clone a repository

Build your own SQLite

Build your own SQLite

Learn about B-Trees, the foundation of every relational database. Explore TypeScript's API for reading/writing files, and handling custom file formats.

Print page size

Print number of tables

Print table names

Count rows in a table

Read data from a single column

Read data from multiple columns

Filter data with a WHERE clause

Retrieve data using a full-table scan

Retrieve data using an index

Build your own BitTorrent

Build your own BitTorrent

Learn about .torrent files and the famous BitTorrent protocol. Implement your own BitTorrent client in TypeScript.

Decode bencoded strings

Decode bencoded integers

Decode bencoded lists

Decode bencoded dictionaries

Parse torrent file

Calculate info hash

Download a piece

Download the whole file

Magnet Links

Parse magnet link

Announce extension support

Send extension handshake

Receive extension handshake

Request metadata

Receive metadata

Download a piece

Download the whole file

Build your own DNS server

Build your own DNS server

DNS is a protocol used to resolve domain names to IP addresses. In this challenge, you'll build a DNS server that's capable of responding to basic DNS queries.

Along the way you'll learn about the DNS protocol, DNS packet format, DNS record types, UDP servers and more.

Setup UDP server

Write header section

Write question section

Write answer section

Parse header section

Parse question section

Parse compressed packet

Forwarding Server

Many more to come...

coming soon

We release new challenges based on user votes. Let us know what you'd like to see next!

challenge voting

Vote on upcoming challenges

RECENT ACTIVITY 0

“ There are few sites I like as much that have a step by step guide. The real-time feedback is so good, it's creepy!

Ananthalakshmi Sankar Automation Engineer at Apple “ I think the instant feedback right there in the git push is really cool. Didn't even know that was possible!

Patrick Burris Senior Software Developer, CenturyLink