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CodeplainerAI Voice Tutor for Code

Company
Founder-built SaaS
Period
2026
Role
Founder. Product, design, full-stack, launch
Shipped
codeplainer.com, live with paid plans
Visit codeplainer.com

Context

A new wave of people ship working apps with Cursor, Claude Code and Lovable without understanding what they built. When something breaks they are passengers in their own codebase. Chat tools hand them another answer to paste, which fixes the bug and teaches nothing.

Landing page, with a call in progress
The Codeplainer landing page: the headline 'Get on a call with an AI that teaches code like a senior engineer.' above a product demo of a call. A Stripe webhook route is open with its lines highlighted, a strip traces how an order travels from the pay button to the orders table, and the tutor answers 'what is a webhook?' in the call panel.

The problem

Make learning from your own code feel like sitting next to a patient senior engineer, somewhere a beginner can ask the same basic question five times without feeling behind.

What I did

  1. Chose a live voice call over a chat window. The learner can interrupt, ask again or say "slower", the way they would with a colleague.
  2. Synced the voice to the screen. As the tutor explains, it opens the file and highlights the lines it is talking about, or draws an example on the spot.
  3. Gave the tutor a memory of each learner (their goal, what they have covered, what keeps tripping them up) so every call picks up where the last one ended.
  4. Priced by call time rather than tokens, so every call ends with a plain line saying what it cost.
  5. Rebuilt it once already. Version one explained code, version two teaches it, after watching that explanation alone did not stick.

Methods and tools. Next.js, TypeScript, Supabase, OpenAI Realtime, Polar

What changed

Live at codeplainer.com with Pro and Max plans, and free call time to try it first. Designed, engineered and shipped solo alongside a full-time role.

  • Real-time voice with synced code highlighting
  • Remembers each learner between calls
  • Live with a free trial and paid plans