How this founder built a better Duolingo with Codex | William Imoh

William Imoh is the founder of Hackmamba, a developer marketing company, and the creator of Mural, a real-time voice app he built to learn Norwegian after moving from Dubai to Norway. He has a chemical engineering degree, taught himself to code, and spent four years as a product manager, but he had never written a line of Swift. In this episode, William shows how he used Codex and GPT-Live to build Mural natively for iOS and Android, then walks through the Lord of the Rings–themed Grok Bot “fellowship” that helps him run a team of about 25 as a solo founder.

What you’ll learn:

1. The design prompt that made Mural look nothing like any other language app
2. Why 1,000 days of Duolingo left him unable to hold a conversation in Norwegian
3. What GPT-Live-1 costs per session and the latency threshold that makes or breaks a voice tutor
4. How he assigned every solo founder role to a Lord of the Rings character in Grok
5. Why he gave his agents access to everything across 15 open tabs, except one thing
6. What he still has to do himself after the models improved
7. Why the fear that keeps him up isn’t replacement—it’s dependency

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In this episode, we cover:

(00:00) Teaser

(02:52) Introduction to William and his language learning app

(05:58) William’s tech background and how he started building

(08:07) The first prompt

(11:09) The importance of design language and articulation

(14:38) Live demo: a Norwegian conversation

(21:11) Having a growth mindset

(22:48) Why GPT Live works for this

(23:34) What it costs to run

(24:50) Running Hackmamba with agents

(26:58) Codex projects for organization

(28:47) His Lord of the Rings Grok Bot fellowship

(34:05) Recap

(34:54) Prompting strategies

(37:21) Where to find William

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References:

• Mural on GitHub: https://github.com/Chuloo/mural

• Codex: https://chatgpt.com/codex

• GPT-Live: https://openai.com/index/introducing-gpt-live/

• Grok Bot: https://grokbot.com/

• Cursor: https://cursor.com/

• Boki: https://boki.io/

• Notion: https://www.notion.com/

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Where to find William Imoh:

X: https://x.com/iChuloo

LinkedIn: https://www.linkedin.com/in/william-imoh

Hackmamba: https://hackmamba.io/

Hackmamba Podcast: https://hackmamba.io/eoc-podcast/

Mural: https://mural.chat/

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Where to find Claire Vo:

ChatPRD: https://www.chatprd.ai/

Website: https://clairevo.com/

LinkedIn: https://www.linkedin.com/in/clairevo/

X: https://x.com/clairevo

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Production and marketing by https://penname.co/. For inquiries about sponsoring the podcast, email jordan@penname.co.