How I Solo Built Complete Interview Prep (From Idea to Users)

I built Complete Interview Prep solo.
No co-founder.
No agency.
No VC money.

Just a very specific problem I had personally—and a lot of stubborn execution.

This post is a breakdown of why I built it, how I built it & what worked. If you’re an indie hacker building alone, this is for you.

The Problem I Experienced First-Hand

I had already built another product in the same space: Game Assessment Prep, focused on HireVue game-based assessments.

What I kept seeing from users was consistent:

They could practice games
They could understand logic and scoring
But video interviews were still killing them

Not because they were unprepared on content—but because:

They didn’t know how they looked on camera
They didn’t know how answers were actually evaluated
They had no realistic way to practice under pressure

Most “interview prep” products are:

Static PDFs
Generic questions
Human coaches that don’t scale and cost too much

I wanted something different:

A product that simulates the interview, evaluates you like a recruiter, and gives actionable feedback—automatically.

That’s how Complete Interview Prep started.

Why I Built It Solo

Short answer: speed and control.

Long answer:

I already had domain expertise (interview assessments)
I already knew the user pain extremely well
I didn’t want alignment discussions before validating demand
I wanted full control over UX, pricing, and iteration speed

Solo building meant:

Faster decisions
Fewer compromises
Brutal accountability

If it failed, it was on me.
If it worked, I’d know exactly why.

The Core Product (MVP Scope)

I forced myself to keep the scope tight.

Complete Interview Prep does only one thing well:

It lets users practice realistic interviews and get structured AI feedback.

Core features:

Video interview simulations
Role-specific interview questions
Custom interview creation
AI evaluation on clarity, structure, confidence, and relevance
Actionable feedback, not generic tips

No community.
No job board.
No fluff.

Everything else was noise.

Tech Stack (Solo-Friendly by Design)

I optimized for speed, reliability, and low maintenance.

Frontend: React + Tailwind
Backend: Supabase (auth, DB, storage)
AI stack:
- Whisper for transcription
- Gemini + GPT-4o for evaluation and scoring
- Structured JSON outputs (non-negotiable)
Payments: Stripe
Hosting: Vercel
Automation: Make.com for glue logic

Key principle:

If something required babysitting, I didn’t ship it.

The Hard Part Nobody Talks About: Evaluation Logic

The hardest problem wasn’t AI generation.

It was scoring.

Users don’t trust vague feedback like:

“Good answer”
“Needs improvement”

So I had to design:

Clear evaluation dimensions
Consistent scoring logic
Deterministic output formats
Feedback users could act on

This meant:

Iterating prompts dozens of times
Forcing models into strict schemas
Rejecting “creative” answers from AI
Treating feedback like a product, not a feature

This took more time than the entire frontend.

Pricing Strategy (No Overthinking)

I didn’t A/B test endlessly.

I went with:

Free: limited interviews
Plus: serious candidates
Premium: heavy users and job switchers

Why subscriptions?

Predictable revenue
Clear value progression
Easier to optimize LTV over time

Most importantly:

Pricing filtered users who actually cared.

Support tickets go down.
Feedback quality goes up.

Launch Strategy: No Big Bang

I didn’t do a flashy launch.

Soft-launched to existing users from my other product
Posted in relevant communities
Wrote SEO-driven content early
Iterated based on real usage, not opinions

Indie lesson:

Distribution beats polish every time.

What Worked

Building for a pain I personally had
Shipping fast and improving weekly
Saying no to “nice-to-have” features
Treating AI as infrastructure, not magic
Keeping costs extremely low

Advice If You’re Building Solo

Start from a problem you deeply understand
Keep scope painfully small
Ship something useful, not impressive
Treat AI like a system, not a shortcut
Charge earlier than you’re comfortable with

Solo building isn’t easy—but it’s incredibly clarifying.