Promo Instant Image Resizer - Automatically optimize images for web & social media (free!)
Bannerbear - Auto-generate IG Stories, Pinterest Pins and more
Responsive Image Breakpoint Generator - Turn one image into the ideal set of per-device images
APITemplate.io - APITemplate.io allows you to auto-generate social images and PDF documents with a simple API or automation tools like Zapier & Airtable. No CSS/HTML required.
Placid - Use Placid to auto-generate images, videos & PDFs from reusable templates
Airtable - Airtable works like a spreadsheet but gives you the power of a database to organize anything. Sign up for free.