The software development principle known as “You Aren’t Gonna Need It” (YAGNI) is one that many teams struggle to apply effectively. YAGNI recommends building only essential features for the current requirements and avoiding unnecessary complexity or premature optimization.
On the surface, YAGNI makes a lot of sense. Why waste time engineering things that users don’t need yet? But knowing when to apply YAGNI and when to think ahead requires judgment and experience. Use it too aggressively, and you risk technical debt or paint yourself into a corner. Don’t apply it enough, and you may take on excessive complexity that slows you down.
Origins of YAGNI
Ron Jeffries, one of the founders of Extreme Programming, often told his development teams, “You aren’t gonna need it!” whenever they wanted to add features or code that wasn’t required for the current user story they were working on.
The teams would insist that they implement certain functionality because it might be useful later. But Jeffries recognized this as unnecessary complexity that would only slow down development.
Instead, he advocated strictly focusing on only what’s needed for the current requirement and avoiding potential future features or unnecessary optimizations. Over time, this concept became known as YAGNI — an acronym for “You Aren’t Gonna Need It.”
Jeffries tells a story of when the team wanted to build a framework for a future reporting feature because they thought reports would be useful someday. But he pushed back, saying, “YAGNI, do the simplest thing that could work for now.” The team ended up not needing that reporting system for a long time.
This exemplified the YAGNI philosophy — if a feature isn’t immediately required, it’s best to refrain from building it proactively. Jeffries would remind teams, “You Aren’t Gonna Need It,” whenever they steered outside what was essential for the current requirements. That abbreviation stuck and became known as the YAGNI principle.
Benefits of YAGNI
When applied properly, YAGNI can really streamline software development. Avoiding the features nobody asked for keeps things simple and stops scope creep. Why spend a ton of time building stuff end users don’t need? That’s just a waste of time and energy.
YAGNI helps teams stay laser-focused on must-have features and getting feedback. When you cut out the fat, you’ll be amazed how much faster development can move. The best part is how quickly you can deliver real value to users this way. YAGNI helps you build a truly lean software machine. Here are some details about the advantages of this principle.
YAGNI helps avoid feature creep and keeps things simple by only building what you need right now. Instead of over-engineering with fancy features, abstractions, and optimizations nobody asked for, it forces you to focus on core functionality. This makes the system way easier to understand and modify later on. For example, on an e-commerce site, you’d first concentrate on core checkout flows instead of jumping into advanced recommendations. Gotta walk before you can run!
Avoids wasted effort
YAGNI stops you from working on stuff that doesn’t deliver value. If customers aren’t asking for it yet, it’s likely just a waste of precious engineering time. There is no need to optimize performance for a million users on day one if you only have a hundred signups. Avoid premature optimization and stick to problems users actually have today.
Enables faster development and feedback
Cutting out unnecessary work really speeds things up and enables faster feedback. If you ignore cooler-sounding features that aren’t critical, you can build faster and get user feedback quicker. Who cares if you have fancy permission controls if users are only going to use basic accounts? Resist rabbit holes and keep the feedback loop tight.
Easier to maintain and change
Keeping things simple upfront prevents you from painting yourself into a corner down the line. Changing things later is way easier if you avoid big, complex architectures when you don’t need them. Don’t abstract things to death unless you absolutely have to. Follow YAGNI and retain flexibility.
YAGNI keeps everyone laser-focused on the current requirements of the product owner, not distractions. If chatbots are off the roadmap for a while, wait to let the engineer build a slick bot platform just because it’s cool tech. Stick to the current roadmap only.
Less code means fewer bugs
Limiting code means limiting bugs. The more code you have lying around and the more abstract and complete it is, the more issues you’ll have. If you build big systems before you need them, a ton of unused code is not even being tested. Keep it lean and maintain quality by only building the essentials.
Delivers value early
YAGNI pushes you to crank out the most important stuff first. Keep finishing the critical user journeys in sight by avoiding diving into rarely used features or edge cases. Knock out what matters first. Maximize value by sticking to must-haves.
Potential Downsides of YAGNI
You can go overboard with YAGNI, too. If you aren’t careful, it can bite you later. Removing too many guardrails can make the system kludgy and hard to modify when requirements change, especially for less experienced team members.
In the same way, if you only listen to users today without thinking ahead, you may miss the boat on what they need tomorrow. And if you only copy/paste code without building reusable components, things get messy quickly.
Some strategic design up front, like planning future APIs, can really pay off. You gotta find the right balance between moving fast now and preventing major rework down the line. Use your best judgment here.
Going overboard with YAGNI can make adding new features more messy. If you don’t build any flexibility upfront, tacking on new capabilities gets tricky. For example, not considering APIs makes connecting mobile apps a giant headache. Consider how likely it is to need something the future so you don’t paint yourself into a corner.
Super lean systems can backfire if priorities suddenly shift. When you only focus on today, changing direction tomorrow is tough. If you don’t anticipate search needs even a little, adding it later is a beast. Give yourself some wiggle room in case plans change.
Dependency accurate requirements
YAGNI depends a lot on correctly guessing what users will want long-term. Just listening to current requests may miss the mark on actual needs down the road. Users might say they don’t need data exports, only to change their minds later. Gotta go beyond the surface to truly understand needs.
Makes it harder to extend the system
If you aren’t careful, YAGNI can create a messy tangle of code that fights any changes. Lack of modularity means adapting to new requirements is brutal. If you don’t separate concerns, adding something like reporting gets ugly quickly. Balance YAGNI with some high-level design thinking.
Going way overboard with YAGNI can lead to copy-paste madness. When you avoid general solutions, you end up reinventing wheels. Building UI modules with no reuse leads to duplication mess. Some upfront component thinking, even if simple, avoids headaches.
Delays building foundational components
YAGNI can put the brakes on foundational stuff that paves the way for key future capabilities. Even though user management seems irrelevant now, it will still unlock collaboration features later. Look ahead a little at pillars that will be important down the line.
Upfront design and thinking add value
Even with YAGNI, some high-level design sessions pay off big time. If you know reports are coming, plan the data architecture. Avoid analysis paralysis, but do think through likely future scenarios to grease the wheels for key functionality. Find the right balance for your unique situation.
Finding the Right Balance
When it comes to YAGNI, no hard rules work perfectly every time. Like most things in software development, you gotta use good judgment and experience to figure out the right balance for your situation.
Use YAGNI as a handy rule of thumb to build only what you need for now. It’ll help you avoid waste and stay focused on delivering value fast. But don’t take it as gospel — sometimes you gotta use your noggin and think a bit ahead.
You want to avoid taking YAGNI so far that you build a flimsy house of cards that’ll fall apart later. But you also gotta avoid over-engineering things upfront that nobody needs yet. It’s a tightrope walk, for sure.
With some practice, you’ll get better at spotting when to lean on YAGNI and when to look further ahead down the road. Finding that sweet spot is an art — you build simple yet solid yet flexible yet focused software.
So use YAGNI wisely. Keep it in your back pocket to stay lean, but don’t be afraid to pause and consider the bigger picture, too. Building great software means delivering value today while also setting yourself up for sustainable success in the long run.
Originally published on Medium.com