Terms and conditions
Last updated: November 13, 2026
1. Provider and service
castly (castly.sh) offers an API, a browser SDK and a dashboard to send web push notifications to the subscribers of your websites and PWAs. It is provided by Fersoft Technologies, LLC, a limited liability company organized in Delaware (file number 10321376), with its address at 1111B S Governors Ave STE 39885, Dover, DE 19904, United States. Contact: hola@castly.sh. By creating an account or using the service you accept these terms.
2. Account and keys
You must be an adult and give accurate details; if you use castly for a company, you accept these terms on its behalf. Every account has one organization. Keep your password and your secret API keys safe, do not publish them in the browser or in repositories, and revoke them if they leak. You are responsible for what is done with your account and your keys.
3. Your subscribers and your notifications
You decide whom you ask for permission, what you send and when. You are responsible for having a legal basis to send your notifications (the browser permission may not be enough in your country), for informing your subscribers in your privacy policy, for handling their rights and for the content, links and images of your notifications. The content remains yours; you authorize us to process it only as needed to deliver it and show it to you in the dashboard.
4. Acceptable use
You may not use castly to send spam, phishing, malware or deceptive notifications (for example, ones that imitate system alerts, a bank or another brand, or hide where they lead); for illegal content; to send to people who have not subscribed; or to get around the limits of the service or attack it. We may suspend organizations that abuse the service: meanwhile, the API rejects their sends (403 org_suspended). We will tell you and you can appeal where appropriate; in serious cases the suspension may be immediate.
5. Plans, quotas and prices
The Free plan costs nothing and includes 10,000 pushes a month and 1 project. Pro includes 250,000 pushes a month and 5 projects for US$15 a month. Scale includes 2,000,000 pushes a month and 25 projects for US$79 a month. All of them include unlimited subscribers, webhooks, export and delivery logs for 30 days.
A push is one delivery attempt to one device. The quota is per calendar month (UTC) and shared by every project in the organization. When it runs out, sending stops until the next month or until you upgrade.
Prices are in US dollars. Before paying, check the price, currency, taxes and billing period on the Stripe screen: those are the amounts actually charged. We may change prices for future periods with reasonable notice; no change affects a period already paid.
6. Renewal, cancellation and refunds
Paid plans start when Stripe confirms the payment and renew every month until you cancel from Billing, in the dashboard. If you cancel, you keep the plan until the end of the paid month and the Free plan limits apply afterwards. As a rule, partial periods are not refunded, without prejudice to withdrawal and other legal rights.
7. Consumer right of withdrawal
If you sign up as a consumer from the European Union, you may withdraw without giving a reason within 14 calendar days of signing up by writing to hola@castly.sh. If you asked for the service to start earlier and then withdraw, we may charge the proportional part of the service provided where the law allows it. We will refund what is due with the same payment method within 14 days.
8. Data processing on your behalf
For your subscribers' data (the push subscription with its endpoint and keys, browser and OS, user identifier and tags if you send them, test device marks and labels, and delivery events), your organization is the controller and we are its processor. We commit to: process it only to provide the service to you and on your instructions (those you give by using the API and the dashboard); not use it for our own purposes or sell it; require confidentiality from whoever processes it; apply appropriate security measures; use only the sub-processors listed in the privacy policy (Cloudflare for infrastructure, queues, database and email) and tell you about changes; help you handle your subscribers' rights and meet your obligations; notify you without undue delay of security breaches that affect them; and delete their data when you delete it or when the service ends, within 30 days. Delivery logs are deleted after 30 days. You can export your VAPID keys and your subscribers anytime with the API or from the dashboard.
9. Delivery and availability
Delivery depends on browsers, on third-party push services (Google, Mozilla, Apple, Microsoft…) and on each device: it may be offline, have notifications turned off or, on iPhone and iPad, not have the site installed. That is why we do not guarantee that every notification is delivered, shown or arrives at a specific time. Webhooks are best-effort and not retried. We work to keep the service running at all times, but it depends on external providers and maintenance, and it may have interruptions. Our liability will be determined under the applicable law; nothing in these terms limits liability that cannot legally be limited or the mandatory rights of consumers.
10. Law, disputes and changes
If you are a consumer, you keep the protection of the mandatory rules of your country of residence and are not required to litigate in Delaware. Before making a claim, you can write to us to try to resolve it. We will publish new terms on the site and give reasonable notice of significant changes; if you disagree, you can cancel, export your data and stop using the service.