How Can You Spot Developers Who Over-Promise Results?

Have you ever been told your app idea could be built in six weeks, only to find yourself still waiting six months later? I've been developing mobile apps for over nine years now, and I can tell you that one of the biggest problems in this industry isn't technical—its the gap between what developers promise and what they can actually deliver. I see it all the time. A client comes to me after working with another agency, frustrated because their "simple" e-commerce app that was meant to take two months has dragged on for half a year, with nothing to show for it but excuses and blown budgets. The thing is, this isn't always malicious; sometimes developers genuinely underestimate the complexity, but other times? Well, they're just telling you what you want to hear to win the contract.

What makes this worse is that clients often don't know what questions to ask. When someone shows you a slick portfolio and promises rapid delivery at a competitive price, it sounds perfect. But here's what I've learned from building apps for startups, healthcare companies, and even Fortune 500 brands—if it sounds too good to be true, it probably is. The developers who over-promise aren't always the ones who seem dodgy; sometimes they're the most confident, the most enthusiastic, the ones who make you feel like your project is the easiest thing they'll build all year. That confidence can be intoxicating, but it can also be expensive.

The best developers I've worked alongside are the ones who ask difficult questions upfront and give you timelines that make you wince a bit—because they're being honest about the complexity involved.

This guide will help you spot the warning signs before you sign a contract and hand over your deposit. We'll look at the red flags in timelines, the questions that separate honest developers from those just chasing a sale, and what realistic project estimates actually look like when you're building a proper mobile app. Because trust me, knowing how to vet developers properly will save you months of headaches and thousands of pounds.

Why Some Developers Promise the Moon

The mobile app development industry has its fair share of cowboys who'll tell you they can build the next Instagram in six weeks for £10,000. I've cleaned up after enough of these projects to know exactly why this happens—and honestly, it's not always because they're deliberately trying to mislead you. Sometimes they genuinely don't know what they don't know, which is almost worse than the ones who are just trying to win the contract.

Here's the thing about over-promising: its often driven by desperation for work rather than malicious intent. Smaller agencies or freelancers who need to keep their pipeline full will sometimes say yes to timelines and budgets that are physically impossible to meet. I've seen developers promise a fully-featured e-commerce app with payment processing, user accounts, and real-time inventory syncing in eight weeks. That's... well, that's just not happening. Even with the best cross-platform frameworks, you're looking at three to four months minimum for something like that, and thats assuming nothing goes wrong (which it always does).

The Most Common Over-Promises

In my experience, there are specific things that developers consistently over-promise on, and knowing these patterns helps you spot trouble before you sign anything:

• Timeline compression—claiming they can build in half the time it actually takes
• Feature scope—saying everything you want is "simple" or "straightforward" to implement
• App Store approval—guaranteeing approval when Apple rejects about 40% of submissions on first try
• User numbers—promising thousands of downloads without any marketing budget or strategy
• Backend complexity—underestimating server infrastructure, database design, and API development time
• Third-party integrations—treating payment gateways, social logins, and analytics as if they're plug-and-play

Another major factor? Some developers simply lack experience with the full app lifecycle. They might be brilliant at writing code but have never actually launched an app to production, dealt with real user feedback, or handled the complexity of ongoing maintenance and updates. Building the app is maybe 60% of the work—the rest is testing, optimisation, submission processes, and post-launch support that many inexperienced developers don't factor into their estimates. When developers underestimate the complexity of features, it's worth understanding which app features drive up development costs so you can spot unrealistic quotes.

Red Flags in Project Timelines

I've reviewed hundreds of project proposals over the years and there's a pattern that shows up again and again when developers are over-promising. The timeline looks perfect. Too perfect, actually. When someone tells you they can build a fintech app with biometric authentication, real-time transaction processing and compliance features in eight weeks, run. I mean it—literally get up and walk away because they're either lying or they've never built anything remotely similar before.

The biggest red flag? No buffer time. Real projects have delays. APIs don't behave as expected, third-party services go down, Apple rejects your first submission for some obscure guideline you didn't know existed (happens more than you'd think). A developer who presents a timeline without any contingency isn't being optimistic—they're being naive or dishonest. When I present timelines to clients, I always include a buffer of at least 20% because that's what years of experience has taught me is realistic. Understanding what happens when your app fails regulatory checks can help you appreciate why experienced developers build in extra time for compliance and approval processes.

Another warning sign is when testing gets squeezed into the final week. I worked on a healthcare app once where the previous agency had allocated just five days for testing a system that handled patient data and appointment scheduling. Five days! The app crashed during user acceptance testing and they had to start over—wasted three months and a lot of money. Proper testing should take roughly 25-30% of your total development time, sometimes more for apps handling sensitive data or complex integrations.

Timeline Red Flags to Watch For

• No contingency buffer or "what if" scenarios included in the schedule
• Testing phase is less than 20% of total development time
• App store submission and approval treated as same-day events (Apple review alone takes 1-3 days minimum)
• Complex features like payment processing or authentication listed with same timeline as simple screens
• No time allocated for client feedback rounds or revision cycles
• Backend infrastructure setup squeezed into a few days

You know what really gives away inexperienced developers? When they treat every feature as equal in their timeline. Building a login screen and building a real-time chat system are not the same thing—one takes a day, the other takes weeks. If someone's giving you a timeline where everything gets roughly equal time allocation, they haven't thought it through properly. Its a massive warning sign that they're guessing rather than planning.

Ask any developer to walk you through their timeline phase by phase and explain what could go wrong at each stage; if they cant identify potential delays or say "nothing will go wrong" then they're not being honest with themselves or you.

Understanding What's Actually Possible

After building apps across healthcare, fintech and e-commerce for the better part of a decade, I can tell you there's a massive gap between what clients imagine is possible and what can actually be delivered. And that gap? That's where over-promising developers thrive. They'll tell you they can build the next Instagram in 8 weeks with a £20k budget—spoiler alert, they cant. Understanding technical limitations isnt about being negative; its about being realistic so you don't waste money on impossible promises.

Here's what I mean. A fintech client once came to me after another agency promised them real-time fraud detection using "advanced AI" in their first release. Sounds impressive right? But building proper machine learning models requires thousands of data points, weeks of training, and ongoing refinement. You can't just flip a switch and have working AI. I've seen this pattern repeatedly—developers using buzzwords like blockchain, AI, or AR to sound sophisticated without explaining the actual work required. Real AI implementation for a finance app takes months of data collection alone, not to mention the regulatory compliance issues that come with it. When developers over-promise on AI capabilities, it's worth understanding what happens when AI gets your app users completely wrong to appreciate the risks of rushing these features.

Platform Limitations Are Real

Some things genuinely aren't possible on mobile platforms, or they require workarounds that add weeks to development. Apple's App Store has strict rules about what apps can access—you cant read other apps data, you cant run intensive background processes for long periods, and certain Bluetooth features are restricted. Android is more flexible but fragmented across thousands of device types. When a developer promises something that pushes these boundaries without mentioning the constraints? That's a red flag. I always walk clients through what their chosen platform can and cannot do before we even discuss timelines.

Feature Complexity Varies Wildly

Not all features are created equal, and this is where estimates can be misleading. A simple login screen might take a day or two. But secure payment processing? That's weeks of work involving PCI compliance, encryption, testing across payment methods, and integration with payment gateways. I worked on an e-commerce app where the client's previous developer estimated the checkout flow at "about a week"—it actually took us nearly six weeks to build it properly with all the security requirements and edge cases. Things like real-time chat, video streaming, or location-based services all sound simple until you're actually building them at scale. For fintech projects specifically, building apps that banks and regulators will trust requires additional layers of security and compliance that inexperienced developers often overlook.

The developers who are honest will break down why certain features take longer. They'll explain the difference between a basic version and a production-ready version. They'll tell you about the testing required, the security considerations, and the backend infrastructure needed. When someone glosses over these details and gives you a suspiciously short timeline... well, they either don't understand the complexity or they're hoping you don't.

Questions That Reveal Developer Honesty

I've learned that the right questions can cut through the sales pitch faster than anything else. When I'm sitting across from a potential client, I know they're trying to work out if I'm being straight with them or just telling them what they want to hear—and honestly, you should be doing the same thing when you're vetting developers.

Start with this one: "What's the biggest technical challenge you see with our project?" If they say there isn't one or everything's straightforward, that's your first warning sign. Every project has challenges. When I worked on a healthcare app that needed to integrate with multiple NHS systems, the data synchronisation was a nightmare—and I told the client that upfront. Real developers know where the difficult bits are because they've built similar things before. For healthcare projects, understanding GDPR compliance requirements for healthcare apps is crucial, and honest developers will explain these complexities upfront.

Ask them to explain what could go wrong and how they'd handle it; vague answers mean they haven't thought it through properly

Here's another good one: "What parts of this project would you recommend we cut or postpone?" Developers who are being honest will help you prioritise. I've had clients come to me wanting 47 features in their first release, and part of my job is telling them which 12 actually matter for launch. If someone says you need everything right away, they're either inexperienced or trying to inflate the project cost.

You can also ask: "Have you built something exactly like this before?" Listen carefully to their answer. Its fine if they haven't—most projects are unique in some way—but they should be able to point to similar work and explain what's different about your requirements. When developers start hand-waving about how "similar" projects are without specifics, that's usually because they're stretching the truth a bit. This is where proper background checks for app developers become essential to verify their claimed experience.

The Difference Between Confidence and Over-Promising

There's a fine line between a developer who knows what they're doing and one whos just saying what you want to hear. I've sat in hundreds of client meetings over the years and I can tell you that the difference isn't always obvious at first. A confident developer will tell you exactly what they can build, what the challenges might be, and roughly how long it'll take based on similar projects they've done before. An over-promiser? They'll nod enthusiastically at everything you say and assure you its all possible within your timeline and budget.

The key difference is in the details. When I worked on a healthcare app that needed to integrate with multiple NHS systems, I told the client upfront that data integration would be complex and might take 6-8 weeks longer than their initial timeline. That's confidence—knowing the technical landscape well enough to spot potential issues before they become problems. An over-promiser would've just said "yeah we can do that" without understanding what was actually involved in securing those data feeds and meeting NHS Digital's technical standards.

Signs of Genuine Confidence

A confident developer will actually push back on some of your ideas, not because they're being difficult but because they've seen what works and what doesn't. They'll suggest alternatives based on real user behaviour they've observed in other apps. They'll talk about trade-offs—like how adding a particular feature might impact performance or increase development time. When I built an e-commerce app for a retail client, I told them their checkout flow had too many steps and showed them data from previous projects proving that simpler flows converted better. That kind of honesty comes from experience, not from trying to win a contract. Understanding how waiting times affect user retention is the kind of insight that experienced developers bring to projects.

The Over-Promiser's Tell

Over-promisers have a few common tells. They rarely ask questions about your users or your business goals; they just agree with everything. They dont mention potential technical constraints or regulatory requirements. They give you a single timeline without explaining what could affect it. I've seen developers promise to build "the next Uber" in three months for £20,000, which is frankly ridiculous when you understand whats involved in building a two-sided marketplace with real-time tracking, payment processing, and user verification systems. Before committing to any development project, it's worth understanding why cross-platform development costs more than expected to spot unrealistic pricing.

Here's what to listen for in conversations:

• Confident developers explain their reasoning and mention similar projects they've completed
• They discuss potential problems before you have to ask about them
• They provide ranges rather than exact figures (because software projects have variables)
• They ask detailed questions about your users, competitors, and business model
• Over-promisers agree to everything without discussing implementation complexity
• They focus on features rather than user outcomes or business goals
• They give suspiciously precise timelines without explaining their methodology

The truth is that experienced developers have been burned by over-promising in the past. We've learned that under-promising and over-delivering builds better client relationships than the reverse. When a fintech client wanted to add biometric authentication to their banking app, I explained that while fingerprint scanning was straightforward, facial recognition would require additional security audits and compliance checks that would add three weeks to the timeline. They appreciated the honesty and we delivered a secure feature that passed all regulatory requirements. That's the kind of outcome you get from confidence rather than empty promises.

How to Check a Developer's Track Record

The portfolio page is where most people start, and yeah it should look professional—but here's what I actually look for when vetting developers. Real apps in the App Store and Google Play that I can download right now. If someone says they built a healthcare app for a major hospital network, I want to see it running on my phone. I've caught developers showing mockups they never actually shipped, or worse, apps they built three years ago that have been abandoned and don't even open anymore.

Download their previous apps and use them for ten minutes. Check the reviews (especially the critical ones) and look at their update history. An app that hasn't been updated in eighteen months tells you something about how they handle ongoing maintenance. I once reviewed a developer's portfolio where every single app had a 2-star rating and complaints about crashes—yet their website showed glossy screenshots and claimed "best in class performance." The App Store doesn't lie. Learning what to look for when studying app store reviews can help you evaluate a developer's previous work more effectively.

What to Look For in Their Previous Work

Ask for case studies with actual numbers. Not "we increased engagement" but "we took daily active users from 2,000 to 15,000 over six months." Real developers can tell you specific metrics because they were involved in measuring success. Also look at the complexity of projects they've handled—building a simple content app is completely different from building a fintech app with biometric authentication and real-time transactions. If you need the latter, make sure they've actually done it before.

Request references from their last three clients and actually call them. Ask what went wrong during the project, not just what went right. Every project hits problems; what matters is how developers handled them.

Red Flags in Track Records

• Portfolio apps that no longer function or were removed from stores
• Only showing design mockups instead of live applications
• Vague descriptions without specifics about their role or contribution
• No apps in your industry (fintech developers need different skills than gaming developers)
• Refusing to provide client references or case studies with data
• Claiming credit for apps where they were just a small contractor

One thing that's a bit mad really—developers who won't let you speak to previous clients are hiding something. I happily connect prospects with past clients because I know they'll hear honest feedback about how we work. Sure, maybe one project ran over budget or had scope creep, but that's normal. What's not normal is refusing to be transparent about your work history. If they get defensive when you ask for verifiable proof, walk away. It's also worth understanding what happens to your IP when developers leave your project to protect yourself if things go wrong.

What Realistic Project Estimates Look Like

When I give clients estimates, I break everything down into phases because that's the only way to be honest about timelines. A simple MVP for something like a fitness tracking app? You're looking at 8-12 weeks minimum—and that's with a focused feature set and no major integrations. I usually tell clients that if someone quotes them 4 weeks for the same scope, they either don't understand what's being asked or they're planning to cut corners you won't notice until its too late.

The thing is, good estimates aren't just about development time; they factor in design iterations, testing cycles, inevitable scope clarifications, and the App Store review process which can add another 1-2 weeks on its own. I've seen projects where the actual coding took 6 weeks but the total timeline stretched to 14 weeks because of proper QA, user testing feedback, and API integration delays that nobody could have predicted. Understanding when to launch your app's beta test is crucial for realistic project planning, as rushing this phase often leads to problems later.

What Should Be Included in Your Estimate

A proper project estimate breaks down like this, and if you're not seeing these elements then something's missing:

• Discovery and planning phase (usually 1-2 weeks to properly map requirements)
• UI/UX design with revision rounds (2-4 weeks depending on complexity)
• Development time for both iOS and Android if needed
• Integration testing and QA cycles (often 20-30% of dev time)
• Beta testing period with real users
• App store submission and review time
• Buffer time for unexpected issues (I always add 15-20% contingency)

Here's what trips people up though—these phases overlap sometimes but not always. You cant start development until designs are mostly locked down, and you definitely cant submit to the App Store until testing is complete. When developers give you a single timeline figure without this breakdown, they're probably just guessing or they've massively oversimplified what needs to happen. I learned this the hard way on an e-commerce project where the client expected 6 weeks total but proper payment gateway integration alone took 3 weeks of back-and-forth with compliance requirements. Before investing more in your project, it's worth understanding what to check before spending more on your app to ensure you're making informed decisions.

Conclusion

Look, finding the right developer isn't about finding someone who tells you what you want to hear—its about finding someone who tells you what you need to know. After working with hundreds of clients over the years, I can tell you that the projects which succeed are the ones built on honest conversations from day one. Not the ones where everyone nodded along to unrealistic promises because it felt good at the time.

The developers worth working with? They're the ones who push back when your timeline doesn't make sense, who explain why certain features will take longer than you'd hoped, and who've got a portfolio showing apps that actually made it to market and stayed there. I mean, anyone can build an app... the real skill is building one that people use six months after launch. That requires experience, not just enthusiasm.

Here's what I'd do if I were choosing a developer today: I'd ask them about their biggest project failure and what they learned from it. I'd request to speak with past clients (not just read testimonials on their website). And I'd compare their estimates against what you've read in this guide—if they're promising your healthcare app in eight weeks or saying they can guarantee a million downloads, you know something's off. Trust your gut on this stuff; if the promises sound too good, they probably are.

Building a successful app takes time, money, and honest collaboration between you and your development team. The developers who respect that reality, who can explain their reasoning clearly, and who show you evidence of their past work—those are the ones who'll actually deliver something worth launching. Everything else is just noise.