Inspiration
Technical interviews are notoriously high-stress, and traditional preparation is fundamentally broken. Algorithmic platforms only test code in silence, completely ignoring spoken communication and technical articulation. Meanwhile, human mock interview coaches charge upwards of $150 per hour, putting realistic interview prep out of reach for most candidates. We built InterviewAce to democratize elite technical coaching. Inspired by the low-latency intelligence of Gemini 2.0 Flash and seamless subscription monetization through RevenueCat, we set out to create an on-demand, 24/7 mock interviewer that combines verbal dialogue, an integrated live-coding IDE, and instantaneous feedback at an accessible price point.
What it does
InterviewAce is an AI-driven technical interview simulator that combines real-time verbal dialogue and an integrated multi-language coding IDE to deliver realistic, high-pressure interview practice. Powered by Gemini 2.0 Flash, it adapts dynamically to a candidate's domain and seniority, runs and tests code in an in-browser sandbox terminal, and generates instant performance scores with calibrated benchmark solutions—all monetized seamlessly through RevenueCat’s freemium quota system and multi-tier subscription paywalls.
How we built it
We built InterviewAce using high-performance Vanilla HTML5, CSS3, and modern JavaScript, featuring a glassmorphism design system with seamless Dark and Light theme support. For the AI engine, we integrated the Google Gemini 2.0 Flash API for sub-second question generation and code evaluation, alongside the browser-native Web Speech and Web Audio APIs for voice recognition, text-to-speech, and synthetic UI sound effects. Monetization was engineered with the RevenueCat Web SDK to manage subscriber entitlements and flexible paywalls, while the entire development and end-to-end validation was accelerated using Google Antigravity IDE's autonomous browser agents.
Challenges we ran into
Our primary challenge was delivering a realistic, low-latency coding and verbal interview experience entirely within the browser without heavy backend infrastructure. We solved this by pairing browser-native Web Speech and Web Audio APIs with Gemini 2.0 Flash’s sub-second inference, preventing conversational lag during live candidate responses. Additionally, cleanly implementing RevenueCat’s entitlement lifecycle and weekly quota gating on a client-side web application required designing persistent local state caches that trigger soft paywalls without disrupting candidate momentum. Finally, maintaining flawless glassmorphism readability across both Dark and Light themes required meticulously re-architecting our CSS tokens for code editors, modals, and terminal windows.
Accomplishments that we're proud of
We are most proud of creating a friction-free, ultra-responsive technical interview platform that genuinely replicates the pressure and depth of a live human engineering interview. Building an in-browser multi-language IDE (JavaScript, Python, C++, Java) with sandbox terminal execution, real-time voice dialogue, and instant Gemini 2.0 Flash code critique—with zero backend server overhead—was a major technical triumph. Above all, seamlessly integrating RevenueCat’s multi-tier subscription engine alongside an adaptable Dark and Light design system turned our vision into a polished, commercially viable product ready for real candidates.
What we learned
Building InterviewAce gave us deep insights into modern subscription architecture with RevenueCat—specifically how value-first freemium quotas (offering 3 high-impact free sessions) and non-intrusive, context-aware paywalls cultivate candidate trust and maximize conversion. Technically, we mastered combining Gemini 2.0 Flash’s rapid inference with native Web Speech and Web Audio APIs to eliminate server overhead and deliver desktop-grade performance directly in the browser. Finally, we experienced the transformative power of agentic development in the Google Antigravity IDE, demonstrating how automated browser verification and iterative AI pair-programming can compress weeks of full-stack engineering into days.
What's next for Interview_ace
Looking ahead, we are expanding InterviewAce into native iOS and Android apps using React Native and RevenueCat’s native mobile SDKs to capture cross-platform App Store and Google Play subscriptions. On the AI front, we plan to implement Gemini 2.0’s real-time bidirectional multimodal audio and vision streaming to critique candidate whiteboard system architecture diagrams and conversational body language. Finally, we are introducing a B2B University & Bootcamp tier via RevenueCat Web Billing, enabling college career centers and engineering accelerators to offer cohort-wide mock interview prep at scale.
Built With
- ai-feedback
- career-prep
- coding-ide
- css3
- dark-mode
- developer-tools
- edtech
- gemini-2.0-flash
- gemini-api
- google-antigravity
- html5
- in-app-purchases
- javascript
- light-mode
- mock-interview
- monetization
- paywall
- revenuecat
- saas
- sandbox-terminal
- speech-recognition
- speech-synthesis
- subscriptions
- web-audio-api
