Solid SaaS that makes you forget about it once implemented, to focus on other business aspects

We are an eGiftCard company that uses SMS as an integral part of user validation and eGiftCard usage flows. Between 2016-2019 (our earliest years) we had employed another programmatic SMS vendor simply due to the cost - we needed to validate our business hypothesis and the cost had to be minimal. Toward mid-2019, when the number of SMSes was at the scale of a few 10,000s, we started getting a lot more complaints about the effectiveness of SMS delivery. And that is when we checked options in the market and went ahead with Twilio - the major reasons we considered were (a.) feedback available on service from fellow startups, and a comparative analysis with other service providers on the dimension of "SMS delivery effectiveness" (b.) ease of integration for our tech team - documentation helped well (c.) set limits for auto top-ups. Since then our SMS usage has grown by a significant factor - 100,000s/quarter and Twilio has been a great fit for us; we don't think about our SMS layer anymore, so I think that's a job well done by Twilio.