What such a service consists of
An AI image generation service is not just a model call. You need request intake and validation, a task queue (generation takes seconds to minutes), integration with one or several model providers, result storage, credit- or subscription-based billing, content moderation and a user account area. The model is only one part; all the engineering is built around it.
Choosing models and providers
You can use ready APIs (OpenAI, Stability AI and others) or deploy open-source models on your own GPUs. APIs are simpler at the start and need no infrastructure, but cost more at scale and depend on the provider. Your own models are cheaper at volume and give control, but require GPUs, MLOps and a team. It often makes sense to start with APIs and partially move to your own infrastructure as load grows.
Task queue and scaling
Generation is asynchronous: a request goes into a queue, workers pick up tasks, and the user gets the result when ready. RabbitMQ or NATS for queues, worker autoscaling for peak load and protection against "expensive" requests matter here. Without a well-designed queue, the service falls over on the first traffic spike or burns the GPU budget.
Billing, limits and abuse
Generation costs money per request, so you need credits or subscriptions, rate limiting and abuse protection. Otherwise a single user with a script can burn a monthly budget in an hour. A transparent pricing model and per-plan limits are not optional — they are a condition for the service to survive.
Moderation and security
Users will try to generate prohibited content, so prompt and output filtering is required. Add watermarks where needed, logging and legal compliance. Security and moderation are designed in from the start, not "later" — reworking them costs more.