Is Dev Tools free to learn?

Yes. Every Dev Tools lesson on CodeMaster is completely free, with no ads. No login required to read the concept notes.

Can beginners follow Dev Tools?

Yes. Each lesson goes concept explanation → code example → interactive demo → quick quiz, so you can follow with no prior knowledge.

How long does Dev Tools take?

Each lesson is about 30–60 minutes. At 1–2 lessons a day you can finish the whole category in roughly 1–2 months.

Build + API — Maven · Gradle · curl · Postman

🎯 After reading this lesson

After finishing this lesson, you will be able to confidently do the following three things.

▸✅ Choose between Maven vs Gradle + understand why to use Wrapper
▸✅ curl + Postman + Newman workflow
▸✅ Automate API regression testing in GitHub Actions

Keep the learning objectives as a checklist and close the lesson once you can answer all of them.

Maven vs Gradle — Java Build Standards

In one line: An automation tool for dependency management, build, test, and deployment.

Item	Maven	Gradle
Released	2004	2007
Syntax	XML (pom.xml)	Groovy / Kotlin DSL (build.gradle)
Expressiveness	Declarative (low)	Imperative + Declarative (high)
Build speed	Slow (~45s)	Fast (~12s, incremental build)
Cache	Weak	Strong (build cache + daemon)
Learning curve	Low	Medium
Android	X	Standard
Korean large companies	Many	Growing trend

Same dependency, different syntax:

xml

<!-- Maven pom.xml -->
<dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-web</artifactId>
</dependency>

gradle

// Gradle build.gradle
implementation 'org.springframework.boot:spring-boot-starter-web'

> 💡 When to use which: New projects = Gradle. Existing Maven projects = keep as is. Spring Initializr also defaults to Gradle.

💻 📌 ./gradlew vs gradle — Version Pinning Is the Key

curl + Postman — API Testing

curl = terminal HTTP client. The standard for CI, debugging, and documentation examples.

Essential options:

▸-X POST — method
▸-H "Header: value" — add header
▸-d '{"key":"value"}' — body (POST/PUT)
▸-i — include response headers
▸-v — verbose (full request and response)
▸-o file — save to file
▸-L — follow redirects

Examples:

bash

# GET
curl -i https://api.github.com/users/torvalds

# POST + JSON
curl -X POST https://api.example.com/login \
  -H "Content-Type: application/json" \
  -d '{"email":"[email protected]","password":"x"}'

# Authorization header
curl -H "Authorization: Bearer $TOKEN" https://api.example.com/me

# File upload
curl -X POST -F "[email protected]" https://api.example.com/upload

Postman = GUI + collaboration features:

▸Collection — API group (shared with team)
▸Environment — dev/stage/prod variables
▸Tests — validate responses with JS (pm.expect(...))
▸Mock Server — fake API responses (frontend development without backend)
▸Newman — run collections via CLI (CI integration)

> 💡 curl is for code examples, CI, and quick debugging. Postman is for team collaboration and complex scenarios. Use both.

💻 📌 Postman + Newman CI — Automating API Regression Testing

💻 📌 Build & API Command Reference

# === Maven ===
mvn clean package                   # Build (includes tests)
mvn clean install -DskipTests       # Skip tests and install to local repo
mvn dependency:tree                 # Dependency tree
mvn -pl module-a clean install      # Specific module in multi-module
mvn versions:display-dependency-updates  # List of available dependency updates

# === Gradle ===
./gradlew build                     # Build + test
./gradlew bootRun                   # Run Spring Boot
./gradlew dependencies               # Dependency tree
./gradlew :module-a:build           # Specific module only
./gradlew build --scan              # Build scan (visualization)
./gradlew clean build --refresh-dependencies  # Ignore cache

# === npm / pnpm ===
npm install                         # Install based on package-lock.json
npm ci                              # Exactly as per lock (CI recommended)
npm update                          # Minor/patch updates
npm outdated                        # List of outdated packages
pnpm install                        # Disk/speed ↑ compared to npm

# === Python ===
python -m venv .venv                # Create virtual environment
source .venv/bin/activate           # Activate (macOS/Linux)
.venv\Scripts\activate              # Windows
pip install -r requirements.txt
pip install -e .                    # For development (editable install)
pip freeze > requirements.txt        # Save current state

# === curl in practice ===
# Measure response time
curl -o /dev/null -s -w "%{\n}" URL
# Check HTTP/2
curl --http2 -I https://example.com
# Headers only (HEAD method)
curl -I https://example.com
# Save and reuse cookies
curl -c cookies.txt -d "user=x" URL/login
curl -b cookies.txt URL/dashboard

🤖 Try Asking AI Like This

Knowing the concepts from this lesson lets you give specific instructions to AI. Not a vague 'fix this,' but a request with the right vocabulary — that's where token savings begin.

▸'Migrate this pom.xml to build.gradle.kts'
▸'Check this dependency graph for conflicts and duplicates'

Why This Reduces Tokens

Without the concepts, even after receiving an AI response you have to ask again: 'What does that mean?' Those follow-up questions are what consume tokens. Learn the concept once and the conversation ends in one go.