What is an LLM service
Quickly learn about LLMs and LLM services.
When people think of chat AI, they tend to think of applications like ChatGPT, Google Gemini, Claude, and DeepSeek, etc. Generally, people sign up for accounts on these platforms and start using them directly on their websites or apps.
How does Optic work?
Optic, however, is a client; it does not directly operate or provide AI chat services. These services are still provided by entities like ChatGPT.
The technology that runs and converses with you is called an “LLM,” or Large Language Model. Different versions or types of models have varying capabilities and styles.
Therefore, to utilize Optic's powerful features, you need to obtain access to a model from what we call an LLM service. Generally, the process is as follows:
Sign Up
Taking ChatGPT as an example, you don't sign up for a ChatGPT app account; instead, you need to create a platform account on the OpenAI Platform. Using LLMs consumes quota, so you may need to link a payment method or top up your account.
Get an API Key
To ensure that only you can use the LLM service through your platform account and to ensure accurate billing, you need to create what is called an API key. This is a string of characters that must be kept confidential; any program can use these characters to access the LLM service through your platform account.
Generally, after logging into the platform, you'll see the words “API Key” clearly displayed in the navigation bar. Later, we'll also show you how to open this interface for a specific LLM service in Optic.
Enter the information into Optic
This step will be explained later.
Summary
In short, an LLM service is an entity that actually provides LLMs for conversational use.
In addition to companies that directly operate large language models—such as OpenAI (which offers ChatGPT) and Anthropic (which offers Claude)—there are providers we refer to as third-party LLM services, such as OpenRouter. These providers aggregate various large language models, making them more convenient and, in some cases, more affordable.
However, this also means that all your chat histories with the LLMs, which may include the sensitive informations, will pass through them. Therefore, you must choose a provider that you—and the majority of people—trust, and it is best to avoid small, privately operated LLM services.