Why InterviewAce costs $10/mo when LeetCode Premium is $35
A reasonable question to ask: if LeetCode Premium charges $35/mo, Exponent $149/mo, Final Round AI $48/mo, and interviewing.io $225 a session — and they're all big, well-funded companies — how is a solo-built tool charging $10/mo and giving away most features free?
The honest answer isn't "we're better than them." It's that we have a structurally lower cost base. Below is the full line-by-line breakdown so you can decide for yourself whether $10/mo is fair, whether the math holds at scale, and whether you should expect us to be raising prices in six months. (Spoiler: we shouldn't need to.)
The fixed costs
InterviewAce runs entirely on Cloudflare's edge platform plus Groq's open-source LLM inference. Both have generous free tiers. Here's every line item:
| Service | Tier we're on | Monthly cost | What it covers |
|---|---|---|---|
| Cloudflare Pages | Free | $0 | The static site (HTML/CSS/JS). 500 builds/mo, unlimited bandwidth, 25K Functions invocations/day. |
| Cloudflare Workers | Free | $0 | The AI proxy + REST API. 100K requests/day. Currently ~22 invocations/day. |
| Cloudflare D1 | Free | $0 | User accounts, progress, feedback. 25M reads/mo, 50K writes/day. Our DB is 86 KB. |
| Cloudflare KV | Free | $0 | Rate limiting. 100K reads/day. |
| Cloudflare DNS | Free | $0 | Authoritative DNS. |
| Cloudflare SSL | Free | $0 | Universal certificates auto-issued. |
| Cloudflare Web Analytics | Free | $0 | Cookieless, no consent banner needed. |
| Groq API | Free | $0 | All AI: Llama 3.3 70B (default), Qwen 3 32B, GPT-OSS 120B, Llama 3.1 8B. Rate-limited but plenty for current volume. |
| Groq Whisper STT | Free | $0 | Voice transcription. |
| Browser SpeechSynthesis | Free | $0 | Text-to-speech (runs in the user's browser). |
| MailChannels (transactional email) | Free | $0 | Up to a few hundred emails/day. |
| Domain (Hostinger) | Paid | ~$1.50/mo | interview-prep.academy, billed yearly. |
| Email (Hostinger) | Paid | ~$2/mo | support@interview-prep.academy mailbox. |
| Total fixed cost | ~$3.50/mo |
That's not a typo. The entire infrastructure costs about three and a half dollars a month. Which means every Pro subscriber pays for ~3 months of full infrastructure. The rest is all margin.
The variable cost — per active user
Variable cost is "what extra do I pay for each additional user?" For SaaS this is usually CPU, database, and outbound API calls. For us it's almost entirely LLM inference.
A typical active user (one who shows up daily for prep) generates roughly:
- ~50 LLM calls per month — practice "AI Explain" requests, Study Coach runs, AI Coach chats
- ~3 voice interview sessions per month — each is ~6 minutes of speech + a scoring call
In tokens, that's roughly:
| Component | Per active user/month |
|---|---|
| Practice "AI Explain" + chat | ~50K input + 30K output tokens |
| Study Coach (full run) | ~10K input + 15K output tokens |
| Voice interview transcription (Whisper) | ~3 × 6 minutes audio |
| Voice scoring + question generation | ~20K input + 10K output tokens |
| Total | ~80K input + 55K output tokens + 18 min audio |
On Groq's free tier this is well within limits — we just pay $0. If/when we outgrow it, Groq's paid tier prices Llama 3.3 70B at about $0.59 per million input tokens and $0.79 per million output tokens. At those rates:
- 80,000 input × $0.59/M = $0.047
- 55,000 output × $0.79/M = $0.043
- Audio transcription (Whisper paid tier): ~$0.10
- Total marginal cost per active user: ~$0.19/month
A $10 Pro subscriber generates roughly $9.81 of gross margin per month after the variable cost. A free user costs roughly $0.19/month at worst, almost always $0 because most free users don't use voice or coach features daily.
What that means at scale
| Scenario | Free users | Pro users | Monthly cost | Monthly revenue | Margin |
|---|---|---|---|---|---|
| Today | ~5 | 0 | ~$3.50 | $0 | –$3.50 |
| At 1,000 free users + 50 Pro | 1,000 | 50 | $3.50 fixed + 50 × $0.19 + 1000 × $0.03 = ~$43 | $500 | +$457 |
| At 10K free users + 500 Pro | 10,000 | 500 | $3.50 + $95 + $300 = ~$400 | $5,000 | +$4,600 |
| At 100K free users + 5K Pro | 100,000 | 5,000 | ~$4,000 | $50,000 | +$46,000 |
(The Cloudflare costs do scale eventually — at 10K Pro users we'd outgrow some free tiers — but the marginal cost stays in the $0.20-$0.40/user/month range. Groq inference scales linearly until you negotiate volume pricing.)
The structural math: infrastructure cost grows linearly with users, revenue grows linearly with users at $10× the rate. There's no theoretical ceiling that forces us to raise prices.
Why competitors charge what they charge
The natural follow-up: "Then how can LeetCode get away with $35/mo? Are they ripping people off?"
No. They have different cost drivers:
1. Hosted on AWS/GCP/Azure at retail rates. The big interview-prep platforms launched 5–10 years ago on AWS, and you can't easily migrate a database with millions of users to Cloudflare D1. Their compute + bandwidth costs are 5–20x what we pay on Cloudflare's edge. That's not us being clever; it's us starting in 2026 instead of 2014.
2. Paid LLM APIs (OpenAI / Anthropic). Most AI interview tools use GPT-4 or Claude under the hood. GPT-4 is ~$2.50 per million input tokens, Claude Sonnet is ~$3 per million. Our Groq path costs ~$0.59 — roughly 5x cheaper for similar-quality output on this kind of task. If a competitor's variable cost per user is $1 and ours is $0.19, they need 5x the revenue to break even.
3. Hired engineers, sales teams, paid marketing. LeetCode has 100+ employees. Each one costs $200K+/year fully loaded. They need $20M+ ARR just to cover headcount. We have one person, $0 marketing spend, and rely on organic traffic + Reddit + Product Hunt. Our break-even number of paying users is in the dozens, not the thousands.
4. VC pressure. A company that raised $20M in Series A at a $100M valuation has to justify that valuation. The fastest way is to charge more and grow ARR. A solo founder bootstrapping has no such pressure — we can price for sustainability, not for the next funding round.
None of these are inefficiencies their fault. They're rational responses to different business models. The point is: if you're paying $35/mo for LeetCode Premium, $9 of that is paying for AWS bills and salaries that don't exist on our side.
So what's the catch with $10/mo?
If it sounds too cheap, here's what you're actually trading off:
- Smaller team — bugs get fixed quickly (often the same day) but you can't expect 24/7 support with named account managers.
- No proprietary content library — our 1,084 hand-curated questions are sourced from MIT-licensed open-source GitHub repos. Real questions, but you could find them yourself if you knew where to look.
- AI scoring, not human scoring — interviewing.io's $225/session gets you a real FAANG engineer for an hour. Our $10 gets you unlimited AI mocks. Different tools, different jobs. Most people benefit from doing 20 AI mocks before booking one human session.
- No fancy features for the sake of features — we don't have a mobile app, gamification streaks beyond the basic counter, or live community chat. We have the things that actually help you do better in an interview.
What this means for indie SaaS in 2026
If you're a developer thinking about building a SaaS, the punchline is: the cost floor for AI-powered tools has collapsed. In 2022 you needed AWS + OpenAI = ~$3/user/month variable cost. In 2026 you can run on Cloudflare's edge + Groq's open-source LLMs and pay $0.20/user/month. That changes pricing math fundamentally:
- You can sustainably charge $5–$15/mo and still have healthy margins
- Free tiers can be genuinely generous (not just "trial then nag")
- A solo founder with 200 paying users at $10/mo = $2,000/mo profit = real income
We're not the first to do this — Tools like Buttondown, Plausible, Fathom Analytics have been doing edge + lean for years. But the AI category specifically has been weirdly stuck on $35–$200/mo pricing because everyone assumed AI was expensive. Open-source LLMs running on optimized inference (Groq's LPU chips) changed the equation. The pricing is finally catching up.
Try it
If you've read this far you probably want to check whether the actual product is any good, not just the spreadsheet. Free tier doesn't require a credit card:
- Practice mode — unlimited MCQs across 23 languages
- Voice interview — Pro feature, but you can preview the setup flow free
- Study Coach — free for everyone, builds a personalized plan from your goal
Honest invitation: if you sign up and the AI scoring feels unfair or wrong, email me with the session ID. I read every one.
Want more posts like this? The full SEO + pricing strategy gets updated as we hit new milestones. If you're building a SaaS and want to talk through your own cost stack, I'll trade you advice for honest product feedback.