Viral Loops is the strongest referral campaign platform in this market — built around proven viral mechanics, with a 14-day trial on every plan. API access starts at $99/mo (Plus). If viral pre-launch growth is the primary goal, Viral Loops is purpose-built for it. If you need a developer API on a free tier with no participant-based billing, Enlist is the better fit.
Key differences
Viral Loops gates its full API behind the Plus plan at $99/mo. Enlist ships the complete REST API, TypeScript SDK, and MCP server on every tier, including free. No plan locks out programmatic access.
Viral Loops bills per participant — the better the campaign performs, the sooner you hit the next tier. Enlist pricing is capacity: signups stored, not signups per month. A spike from a front-page post changes nothing about the bill.
Every Enlist signup returns a permanent referral_code. Passing that code on a later signup stamps referred_by and increments referral_count. The reward structure is yours to build — Enlist doesn't ship a hosted share page or leaderboard, but the tracking data is in the API on the free tier.
Viral Loops has no agent integration. Enlist exposes every waitlist operation over a hosted MCP endpoint — create, add, and read without leaving the coding agent.
Up to 500 signups on the free tier. Add the MCP server and your agent wires the whole integration in one prompt.