Having worked as a key engineer in the core product of a start-up, showing evidence as to how you have contributed to its success

I worked core product at start-up company, how can I add an example document, does anyone have any ideas?

If you’re trying to support OC3 (impact), according to the guide, provide:

  • Employment contract, that shows you’re actually the key engineer, with the high salary
  • 4th letter from your CxO, that will be focused on your contributions to the product and how it impacts the company and clients
  • Designs, diagrams, tech docs, code commits, other sample pieces of your personal work and continuing contribution

@Taner_Basli @Savvkin couldn’t have put it much better. I used a letter from my boss showing how I contributed to the project as a key Engineer, flow diagrams of my code, and the impact in terms of money made or saved using my work.