The slack app is actually really simple right. There is no backend at all except for OAuth. No real database, no sending emails offline, no major UI components.
Also, have you worked on a slack app? It needs some care - like messaging back and forth, etc needs a little familiarity with the API.
Check google doc.
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Hi, sir! I am very interesting in your project. I have checked your google doc and I am sure I can complete it within 2 days.\ Let's have a chat and start work right now. Best regards.