Glific is a free, libre, open source platform. As such you can download and use the codebase for free. While the platform per se is free, it is built on the WhatsApp Business API and there is a cost involved with sending and receiving messages via WhatsApp Business API. The exact cost of this depends on your Business Service Provider (BSP).
Business service provider
Glific today uses Gupshup.io as its BSP. Gupshup rates for India are 0.1 cent (7 paise) for each message sent or received in addition to the Whatsapp rates of 0.66 cent (50 paise) per Business-initiated conversation and 0.4 cent (30 paise) per User-initiated conversation. Please see the details and a cost calculator here.
For messaging volumes greater than 75,000 Gupshup caps charges at $75, and beyond this, only WhatsApp charges will apply.
SaaS platform run by ColoredCow can be availed at the pricing model mentioned here
For technical support to extend Glific features and offerings that are specific your organisation, you can also reach out to the ColoredCow team to assist you at their consulting prices mentioned here.