Some outlined ideas on Agile vs Extreme Programming (XP): What's the Difference?

February 15, 2025 (3mo ago)

Introduction

In software development, methodologies shape how teams collaborate, deliver value, and adapt to change. Two of the most influential approaches are Agile and Extreme Programming (XP). Though often mentioned together, they are not the same. Understanding their differences—and how they can complement each other—can help teams make more informed decisions.

What is Agile?

Agile is a mindset rooted in values and principles for developing software in uncertain, fast-changing environments. The Agile Manifesto, published in 2001, outlines four core values:

  • Individuals and interactions over processes and tools
  • Working software over comprehensive documentation
  • Customer collaboration over contract negotiation
  • Responding to change over following a plan

Agile isn't a single methodology or process. It's a philosophy that promotes iterative development, frequent feedback, and adaptability. Frameworks like Scrum, Kanban, and Extreme Programming (XP) fall under the Agile umbrella.

What is Extreme Programming (XP)?

Extreme Programming (XP) is a specific Agile methodology created by Kent Beck in the late 1990s. XP focuses on improving software quality and responsiveness to changing customer needs through well-defined engineering practices.

Key XP practices include:

  • Test-Driven Development (TDD)
  • Pair Programming
  • Continuous Integration
  • Refactoring
  • Small Releases
  • Collective Code Ownership
  • Sustainable Pace

XP is both a methodology and a discipline that puts Agile principles into concrete, technical action.

Core Principles: Agile vs XP

Iterative Development

  • Agile: Uses sprints or continuous flow to iterate and adapt frequently.
  • XP: Uses ultra-short iterations (even daily) to deliver rapid feedback and continuous improvement.

Customer Collaboration

  • Agile: Encourages customer feedback through regular demos and review sessions.
  • XP: Requires an on-site customer—someone embedded with the team daily to provide constant guidance.

Embracing Change

  • Agile: Plans for change by regularly reprioritizing the backlog.
  • XP: Builds for change with practices like TDD and continuous integration that reduce the cost of late-stage changes.

Team Structure and Roles

  • Agile: Role definitions vary by framework (e.g. Scrum has Product Owner, Scrum Master, Developers).
  • XP: Defines specific roles like Coach, Customer, and Developers with clear responsibilities.

Engineering Practices

  • Agile: Leaves technical practices up to the team's discretion.
  • XP: Mandates specific engineering practices like pair programming and test-first development.

Documentation

  • Agile: Advocates for minimal documentation—"just enough."
  • XP: Relies on clean, self-documenting code and automated tests.

Release Strategy

  • Agile: Releases occur at regular intervals (e.g. every sprint).
  • XP: Encourages frequent, small releases—potentially multiple times per day.

Key Differences

  1. Scope

    • Agile: A set of values and principles. Not prescriptive.
    • XP: A defined methodology with strict engineering guidelines.

  2. Technical Practices

    • Agile: Optional and framework-dependent.
    • XP: Built around specific technical practices (TDD, CI, etc.).

  3. Customer Involvement

    • Agile: Seeks regular feedback.
    • XP: Requires a constant, physical customer presence.

  4. Team Roles

    • Agile: Flexible, often defined by the framework used.
    • XP: Specific roles such as Coach, Customer, Developer.

  5. Release Cadence

    • Agile: Typically 1–4 week sprints.
    • XP: As frequent as daily or multiple times per day.

Similarities and Overlap

  • Both value adaptability, collaboration, and delivering working software.
  • XP is an early, influential Agile framework.
  • Many teams borrow XP techniques like TDD or pair programming even when using other Agile frameworks like Scrum.

When to Use Each

  • Agile: Great for teams seeking flexibility and the ability to adapt their own structure and workflow. Choose a specific framework (e.g. Scrum, Kanban) based on your context.
  • XP: Ideal for engineering-driven teams that prioritize technical excellence, rapid iteration, and can commit to disciplined practices. XP excels in high-change, high-risk environments.

My Take: Modern Web Dev Through an Agile/XP Lens

Let's get real about how these ideas play out in modern web development.

The Good Parts

Many XP practices are baked into modern workflows without us even realizing it. On a recent project using Next.js 14 with React Server Components, we essentially had CI/CD out of the box. Every push ran tests, type checks, and deployed previews via Vercel. Kent Beck would've approved.

Working with Drizzle ORM also fits both mindsets beautifully:

  • Agile-friendly: Super lightweight migrations, fast iteration.
  • XP-friendly: Type safety feels like automated testing built in.

The Reality Check

Some XP practices, like pair programming, don't always translate perfectly to today's workflows. When you're dealing with:

  • Client vs server components
  • Schema migrations
  • Complex state logic
  • Type juggling in TypeScript

...it's hard to sit and code in pairs full-time. Instead, we've shifted toward "mob reviewing" during PRs—still collaborative, but async and scalable.

What Actually Works For Us

In practice, blending both approaches works best:

1. Quick Iterations (But Scoped)

// Instead of a 200-line mega-feature...
const ComplexFeature = async () => {
  // Complex logic
}
 
// Start simple
const SimpleFeatureV1 = async () => {
  // 20 lines that work
}
// Then iterate with types and tests

2. Type-Driven Development

Using TypeScript + Next.js + Drizzle gives us a first layer of tests through types.

// Your types become your first line of testing
type UserAction = {
  type: 'UPDATE' | 'DELETE'
  payload: User
}

If it doesn't type-check, it doesn't ship.

3. Continuous Deployment (With Guardrails)

We use feature flags and phased rollouts instead of full-throttle XP-style releases. It's safer, but still fast.

The Takeaway

Neither pure Agile nor pure XP is perfect for modern teams. But our current tooling—TypeScript, CI, Next.js, analytics, previews—lets us build fast and safely.

Take what works:

  • Short feedback loops ✅
  • Clean, type-safe code ✅
  • Strong CI/CD pipelines ✅
  • Customer input via analytics and monitoring ✅

Be pragmatic. Mix and match. Iterate fast. That's what works today.

Conclusion

Agile and XP are closely related, but serve different purposes:

  • Agile provides the why and what with values and principles.
  • XP delivers the how with specific technical practices.

Successful teams often mix the two—borrowing what works, discarding what doesn't, and continuously refining along the way.

Further Reading:

LinkedIn