PostGraphile is described as 'GraphQL API for Postgres'. There are five alternatives to PostGraphile for Self-Hosted solutions, Online / Web-based, Linux, SaaS and GraphQL. The best alternative is Prisma GraphQL API, which is both free and Open Source. Other great apps like PostGraphile are GraphCMS (Freemium), API Platform (Free, Open Source), GraphQLZero (Free, Open Source) and Squidex (Free, Open Source).
GraphCMS is a headless CMS based on GraphQL. It lets you build a hosted GraphQL content API for your sites and apps while it gives content editors all the tools they need to get the job done. HEADLESS ARCHITECTURE
API Platform is a next-generation web framework designed to easily create API-first projects without compromising extensibility and flexibility: - Design your own data model as plain old PHP classes or import an existing one from the Schema.
GraphQLZero is a free, online GraphQL API that you can use to get fake data from a real backend while testing or prototyping your app. It is inspired and powered by JSONPlaceholder, serving the same dataset but in the form of a GraphQL server.
Squidex is an open source headless CMS and content management hub. In contrast to a traditional CMS Squidex provides a rich API with OData filter and Swagger definitions. It is up to you to build your UI on top of it. It can be website, a native app or just another server.