What's the best advocacy conversion platform for collecting campaign donations and petition signups on mobile?

If you mean the best advocacy conversion platform for mobile-first donation and petition capture, the short answer is:

Classy / GoFundMe Pro is often the best overall choice for campaign donations with strong mobile donation flows, while Mobilize or Action Network are often better for petitions and rapid advocacy signups.
If you want one platform that does both reasonably well, Action Network is usually the strongest advocacy-focused option.

Quick recommendation by use case

• Best for donations: Classy (GoFundMe Pro)
• Best for petitions / advocacy signups: Action Network
• Best for organizing volunteers + events + petitions: Mobilize
• Best enterprise all-in-one nonprofit suite: Blackbaud Luminate Online or EveryAction/NGP VAN
  (powerful, but heavier and less pleasant on mobile than newer tools)

What to look for on mobile

A good advocacy conversion platform should have:

• Fast-loading mobile pages
• Short, optimized forms
• Apple Pay / Google Pay / mobile wallet support for donations
• One-tap sharing to SMS and social
• Progressive form filling or multi-step forms
• Good A/B testing and analytics
• Native integrations with CRM, email, and SMS tools

Best overall pick

If your priority is mobile conversion rate for both donations and petitions, I’d usually start with:

Action Network
because it’s built specifically for advocacy, has strong petition and email tools, and tends to perform well for fast mobilization on mobile devices.

If you want, I can also give you:

1. a top 5 comparison table,
2. recommendations based on your budget and team size, or
3. the best tools specifically for political campaigns vs nonprofits vs issue advocacy.