Sendgrid

The one that carried a lot of the internet's email.

What it is sold for

Sending high-volume transactional email.

The address redirects to https://www.twilio.com/en-us/sendgrid, which is worth knowing before you follow it.

Same shelf

The rest of payments and messaging, alphabetically. Sharing a category is a filing decision, not a relationship.

• Ably
  Hosted realtime messaging with delivery guarantees and presence, sold on what happens when connections drop.
• Anymail finder
  Finds work email addresses from a name and a domain, and charges only for the ones it can verify.
• Applozic did not answer
  Chat and messaging SDKs. The site presents an expired or misconfigured certificate and would not load.
• Braintree
  PayPal's payment platform for merchants who need cards, wallets and PayPal behind one integration.
• EasyPost
  One API across many carriers for rates, labels and tracking.
• FormSpree
  A form backend for static sites, so an HTML form can submit without any server behind it.
• Heybounce
  Email validation before sending, protecting sender reputation from hard bounces.
• Hunter.io
  Finds and verifies professional email addresses from a domain, one of the older tools in this category.

All 29 in payments and messaging