Kit (formerly ConvertKit)

Kit is built around email as the core tool for creators. It includes multiple form styles (popup, inline, slide-in, sticky bar) plus landing pages, all with a drag-and-drop builder. The free plan is genuinely functional: unlimited forms, unlimited landing pages, and subscriber tagging, capped at 1,000 contacts. For creators bootstrapping their audience, the feature-to-cost ratio is hard to beat.

Best for writers, podcasters, and content creators managing everything in one platform. If you're already using ConvertKit or evaluating it, Kit's form tools are more polished than generic popup builders. Segmentation and tagging work directly in Kit, so you can send different content to different subscriber groups without wiring a separate email tool.