You don't need 300 more problems. You need to know what breaks.
Gadfly is a voice tutor for algorithms, system design and behavioral rounds. It talks with you out loud, keeps a journal of every session, names the one place you slipped — quoting you, with a timestamp — and schedules the fix.A voice tutor for algorithms, system design and behavioral rounds. It remembers every session, names the one place you slipped, and schedules the fix.
Four minutes from here to talking to Arkady. One command to install, one to start. Create an account — only if this machine is not only yours.
- No card, no trial clock
- Speech in and out stays on your machine
- $0.09 to $0.22 of your own API key per session
You already did the hours. That was never the problem.
Four posts from engineers who did everything the internet told them to do. Nothing they used could name the specific thing that went wrong.
“the feedback primarily boiled down to a very repetitive you need to go deeper”
Blind · on a $100 mock with a Google L7
“I knew the pieces of what makes a system but didn't have the intuition to put it all together”
Blind · failed Amazon L5 after Grokking and Alex Xu
Volume is not the missing ingredient — a diagnosis is.Volume is not the missing ingredient.
Every product on this market sells you another run at another problem. None of them remembers the last one.Every product here sells another run at another problem. None of them remembers the last one.
Three pictures. That is the whole product.
No screenshot on this page was drawn. They are taken from the running app.
AI mocks are free now. That's the wrong thing to be selling.
So we don't sell it. Run as many mocks as you like — the difference is what exists tomorrow morning.
| Gadflyfree · your key | interviewing.io$0 (AI) | Hello Interview$79 / year | mockingly.ai$0 · $14 / mo | LeetCode Premium$159 / year | Human mock$100–350 / session | |
|---|---|---|---|---|---|---|
| The interviewer speaks back | yes, and you can cut in | listens only, replies in text | no | yes | no | yes |
| Shared whiteboard | both of you draw | no | yes | no | no | yes |
| Remembers your last session | a journal per session | no | no | no | no | only if you rebook the same person |
| Feedback points at your own words | quote + timestamp | rubric score | rubric score | no | no | “go deeper” |
| Help rationed in steps, by rules | six-step ladders | no | no | no | no | depends on the person |
| Repeats scheduled between sessions | spaced, and on new problems | no | no | no | no | no |
| Your voice leaves your machine | never — speech is local | uploaded | n/a | uploaded | n/a | recorded |
Checked against public pricing pages and shipped product code in August 2026. Something wrong or out of date? Tell us and we'll correct it.
The product is free. Here is what it actually costs to run.The product is free. Here is what it costs to run.
Gadfly runs on your machine with your own model key. Nobody pays for someone else’s GPU, so nobody has to charge for one.
Speech in and out costs nothing — both run on your machine. Set a daily dollar ceiling and it stops when it hits it. What it needs, in detail →
Your next session should know about your last one.
Set a goal, pick a track, do one session tonight. Tomorrow the plan is already different — and you'll know exactly why.Set a goal, pick a track, do one session tonight. Tomorrow the plan is already different.
Start tonight — no account neededFour minutes from here to talking to Arkady.