# speedrun.substack.com

- Canonical HTML: https://growth.iangoh.com/sources/speedrun-substack-com-speedrun-substack-com/
- Original source: https://speedrun.substack.com/p/the-lost-art-of-designing-viral-loops
- Domain: speedrun.substack.com
- Latest check: 2026-03-22
- Channels: Referrals

## Cited GrowthDex tactics

- [Sharer-ID URL encoding for viral factor A/B testing](/growth-ideas/sharer-id-url-encoding-for-viral-factor-ab-testing/) - Encode the sharing user's ID into every shared URL so you can calculate viral factor as a cohort-to-cohort ratio and A/B test product changes to increase it.

## Related reading

- [GrowthDex Blog](/blog/)
- [All growth ideas](/growth-ideas/index.md)