How I Built an ATS Resume Builder App for Android (And What I Learned)

After months of watching friends get rejected by job applications they were qualified for, I discovered the real culprit: Applicant Tracking Systems (ATS). Over 75% of resumes are auto-rejected before a human ever reads them. I decided to fix that by building NextCV — a free Android app that creates ATS-optimized resumes in minutes.

Here's everything I learned building it.

The Problem I Was Solving

A close friend of mine — a solid software engineer with 4 years of experience — was applying to 30+ jobs and hearing nothing back. His resume looked beautiful. Designed in Canva. Clean fonts, nice icons, two-column layout.

The problem? Canva resumes fail ATS scanners completely.

ATS software (used by 99% of Fortune 500 companies and most mid-size companies) reads resumes like a plain text document. Multi-column layouts break the parsing. Icons and graphics get ignored. Fancy fonts cause character errors. His resume, which looked great to humans, was essentially unreadable to machines.

He wasn't alone. Most job seekers don't know this.

Why Mobile-First?

The existing ATS-friendly resume builders (Jobscan, Resume.com, Zety) are all desktop-first. But research shows that over 60% of job applications are started on mobile devices.

There was a clear gap: a mobile-native, ATS-optimized resume builder that feels as natural as using any other productivity app on Android.

That became the vision for NextCV.

What Makes a Resume ATS-Friendly?

Before writing a single line of code, I spent weeks studying how ATS systems work. Here's what I learned:

1. Single-column layout
   
   Multi-column resumes confuse parsers. The reading order gets scrambled. A single clean column is always parsed correctly.




2. Standard section headings
   
   ATS systems look for specific keywords: Work Experience, Education, Skills. Creative labels like Where I've Been or My Toolkit get missed.




3. No tables, text boxes, or graphics
   
   These are invisible to most parsers. Any information inside them simply doesn't exist as far as ATS is concerned.




4. Standard fonts
   
   Stick to Arial, Calibri, Georgia, Times New Roman. Unusual fonts sometimes render as garbled characters.




5. .docx or simple PDF
   
   The best ATS parsers handle both, but a "print-to-PDF" from a clean HTML template is typically more reliable than an export from Canva or Figma.




6. Keyword matching
   
   ATS systems score resumes against job descriptions. The closer your language matches the job posting, the higher your score.

Every template in NextCV is built around these six rules from the ground up.

The Tech Stack

I built NextCV as a Flutter Android app backed by a Spring Boot API.

Flutter (Android)

Clean Architecture with feature-first folder structure

Riverpod for state management (code generation via riverpod_annotation)

GoRouter for navigation

Firebase Auth (Google Sign-In)

Secure token storage with flutter_secure_storage

Dio for HTTP

Freezed + json_serializable for type-safe models

PDF generation handled server-side (cleaner output, consistent fonts)

Spring Boot (Backend)

Java 21 with Virtual Threads (spring.threads.virtual.enabled=true)

Spring Security + Firebase token verification

PostgreSQL via Spring Data JPA

Redis for caching and refresh tokens

Flyway for database migrations

iText / OpenPDF for server-side PDF generation

MapStruct for entity ↔ DTO mapping

Soft deletes only — user data is never hard deleted

Why server-side PDF?

Client-side PDF generation on mobile is inconsistent. Fonts render differently, page breaks break, file sizes bloat. Generating on the server gives us full control over the output — pixel-perfect, consistent, ATS-compatible every time.

The ATS Score Feature

The feature I'm most proud of is the real-time ATS score.

After building a resume, NextCV analyzes it across four dimensions:

Keyword match — does it contain industry-standard terms?

Formatting — single column, standard headings, no tables?

Readability — sentence length, action verbs, quantifiable achievements?

Completeness — are all critical sections filled in?

The score is displayed as a percentage with actionable improvement tips. Users can see their score jump in real time as they edit.

Building this was surprisingly hard. The scoring algorithm went through 11 iterations before I was happy with it. The biggest challenge was avoiding false positives — a highly creative resume for a graphic designer shouldn't be penalized the same way as an engineer's resume.

The AI Content Suggestions

One of the most common user blockers is the blank page problem — people don't know what to write in their summary or experience descriptions.

NextCV integrates AI to generate:

Professional summary paragraphs tailored to job titles

Bullet-point experience descriptions with action verbs

Skills suggestions based on job role

The AI doesn't replace the user — it gives them a strong starting point they can edit. This alone cut our average resume completion time from 23 minutes to 8 minutes in beta testing.

The Biggest Mistakes I Made

Mistake #1: Building the perfect architecture before validating the idea

I spent 3 weeks setting up the perfect Clean Architecture, CI/CD pipelines, and testing infrastructure before talking to a single user. Classic over-engineering. I should have validated with a prototype first.

Mistake #2: Underestimating PDF complexity

PDF generation sounds simple. It's not. Font embedding, page margins, unicode characters, line height, table-free layouts — every edge case took 2–3x longer than estimated.

Mistake #3: Ignoring onboarding

My first beta had a 60% drop-off on the first screen because I asked for too much information upfront. Redesigning the onboarding flow to be progressive (ask for the minimum, reveal more later) doubled completion rates.

Results So Far

NextCV launched on the Google Play Store and within the first month:

10,000+ resumes created

4.8/5 average rating

Users in 15+ countries

Average ATS score improvement: from 52% → 87% after using the app

The most rewarding feedback: "I got 5 interview calls in 2 weeks after using NextCV. My previous resume wasn't getting any responses."

What's Next

The roadmap includes:

Job description analyzer (paste a JD, get keyword gap report)

Cover letter generator

Resume version A/B testing

iOS version

Try NextCV

If you're job hunting or know someone who is, NextCV is free to download on Google Play.

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