Open-source alternative
for Customer.io
Customer.io is powerful but complex. Plunk gives developers the automation they need without the enterprise overhead.
Simple Pricing That Scales
Transparent pay-as-you-go vs complex enterprise tiers
Pay per email sent
Pay-as-you-go pricing. Only pay for emails you actually send.
Complex usage-based pricing
Pricing based on profiles, messages, and feature tiers.
Feature-by-Feature
Key Advantages
Why developers choose Plunk
Developer-First Experience
Clean, simple APIs designed for developers. No complex visual builders or marketing jargon. Integrate in minutes, not weeks.
Transparent Pricing
Pay-as-you-go pricing with no hidden costs or complex tiers. No need to pay for contact lists or profile counts - just emails sent.
Open Source
AGPL-3.0 licensed. Inspect the code, contribute features, fork if needed. No vendor lock-in with proprietary platforms.
Quick Setup
Minutes to integrate and start sending. No lengthy onboarding, no sales calls, no enterprise setup processes. Start free immediately.
Self-Hosting Option
Run on your infrastructure with Docker. Full data control, compliance-ready. Pay only AWS SES fees when self-hosting.
Simplicity at Scale
Simple workflows that scale without over-engineering. Get enterprise capabilities without enterprise complexity or dedicated ops teams.
Frequently asked questions
When should I choose Customer.io over Plunk?
Choose Customer.io if you need advanced behavioral segmentation, visual journey builders, and have a dedicated marketing operations team. Customer.io excels at complex, enterprise-level marketing automation with sophisticated visual tools. Choose Plunk if you want developer-friendly APIs, simpler workflows, and don't need the overhead of an enterprise marketing platform.
What is the pricing difference between Plunk and Customer.io?
Plunk uses a simple pay-as-you-go pricing model where you only pay for emails sent. Customer.io has complex usage-based tiers that combine messages sent, active profiles, and feature access. For small to medium teams, Plunk is typically more cost-effective. Customer.io's pricing scales with contact count and feature usage, which can become expensive as you grow.
Is migration from Customer.io to Plunk complex?
Migration complexity depends on your current setup. If you use basic transactional emails and simple workflows, migration is straightforward - update your API integration and recreate your workflows. If you rely heavily on Customer.io's visual journey builder and advanced behavioral segmentation, you'll need to simplify some workflows. Most teams can migrate in a few days of development work.
What does Plunk simplify compared to Customer.io?
Plunk removes enterprise complexity while keeping core functionality. You get a clean, developer-first API instead of complex visual builders. Workflows are defined in code or simple UI, not elaborate journey maps. Pricing is transparent pay-as-you-go instead of tiered complexity. Setup takes minutes instead of weeks. Plunk is open-source and self-hostable, giving you full control without vendor lock-in.
Try Plunk free
1,000 emails/month free. No credit card required. Developer-friendly from day one.