Yes, both Trello and Customer.io offer a Free Trial.
Trello is designed for Individuals, Freelancers, Large Enterprises, Medium Business and Small Business.
Customer.io is designed for Large Enterprises, Medium Business and Small Business.
Pricing for Trello Starts at $5/User/Month when Billed Yearly whereas for Customer.io Starts at $100/Month.
Some top alternatives to Trello includes Smartsheet, Miro, Process Street, Wrike, Notion, Freshbooks, Jira, Basecamp, Zoho Projects, monday.com, Asana, Teamwork, ProjectManager.com, Microsoft Project, Worksuite, Trackboard, Quick Base, Todoist, ClickUp, Resource Guru and Height.
Some top alternatives to Customer.io includes Outgrow, ActiveCampaign, CleverTap, Moosend, Omnisend, ActiveTrail, Iterable, Hubspot Marketing Hub, Klaviyo, SendGrid, MailChimp, StreamSend, Adobe Marketo Engage and Contactspot.