---
title: Chatbot API - Build AI Chatbots with LLMs | ModelsLab
description: Build AI chatbots with our LLM-powered chatbot API. Streaming responses, custom prompts, and open-source models. Start building free.
url: https://modelslab-frontend-v2-927501783998.us-east4.run.app/chatbot-api
canonical: https://modelslab-frontend-v2-927501783998.us-east4.run.app/chatbot-api
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generated_at: 2026-04-06T12:58:31.175250Z
---
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Chatbot API - Build AI Chatbots with LLMs
---
ModelsLab's Chatbot API provides access to 10+ LLMs including DeepSeek, Llama 3, and Mistral through an OpenAI-compatible endpoint. Build conversational AI with streaming responses, function calling, and multi-turn context. Pricing starts at $0.20 per million tokens with 500ms average latency.
[Build Your Chatbot Now](https://modelslab.com/register) [API Documentation](https://docs.modelslab.com)
What Is the ModelsLab Chatbot API?
---
### A Unified API for Conversational AI
The ModelsLab Chatbot API provides developers with a single REST endpoint to access multiple large language models including Llama 3.1, Mistral, DeepSeek R1, Qwen, and specialized fine-tuned variants. Instead of managing separate integrations for each model provider, you send requests to one API and switch models by changing a single parameter — the model\_id.
The API follows an OpenAI-compatible chat completions format, which means existing codebases built for OpenAI can migrate to ModelsLab by changing the base URL and API key. This compatibility extends to streaming responses via server-sent events, function calling, JSON mode for structured output, and conversation history management.
- Access Llama, Mistral, DeepSeek, Qwen, and other open-source LLMs through one endpoint
- OpenAI-compatible format — migrate existing code by changing base URL
- Streaming responses with server-sent events for real-time chat UX
- Function calling and JSON mode for structured data extraction
- System prompts for chatbot personality and behavior control
- Pay-per-token pricing starting at $1.50 per million tokens
### How Does ModelsLab Compare to Other Chatbot APIs?
ModelsLab differentiates from direct model providers (OpenAI, Anthropic) by offering access to open-source models without infrastructure management. Compared to platforms like Together AI and Groq, ModelsLab provides a broader model catalog including image, video, and audio models alongside LLMs — enabling multimodal chatbot experiences through a single API key.
Pricing is competitive: DeepSeek R1 costs $2.40 per million tokens on ModelsLab, Qwen models range from $2.00 to $3.60 per million tokens, and Llama models start at $1.50 per million tokens. There are no minimum commitments — you pay only for tokens consumed.
### When Should You Use This API?
The ModelsLab Chatbot API is designed for developers building conversational features into applications — customer support bots, AI assistants, content generation tools, and interactive tutoring systems. It is particularly suited for teams that need access to multiple LLM options without locking into a single provider, or teams building multimodal AI products that combine chat with image generation or voice synthesis.
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How Do You Send a Chat Request?
---
Build a working chatbot in minutes with these code examples. The API follows an OpenAI-compatible format for easy migration.
### cURL — Chat Completion
bash
```
1curl -X POST https://modelslab.com/api/v6/llm/chat \
2 -H "Content-Type: application/json" \
3 -d '{
4 "key": "your_api_key",
5 "model_id": "deepseek-r1",
6 "messages": [
7 {"role": "system", "content": "You are a helpful assistant."},
8 {"role": "user", "content": "Explain how transformers work in 3 sentences."}
9 ],
10 "max_tokens": 512,
11 "temperature": 0.7
12 }'
```
### Python — Streaming Chat
python
```
1import requests
2
3response = requests.post(
4 "https://modelslab.com/api/v6/llm/chat",
5 json={
6 "key": "your_api_key",
7 "model_id": "llama-3.1-70b",
8 "messages": [
9 {"role": "system", "content": "You are a customer support agent."},
10 {"role": "user", "content": "How do I reset my password?"}
11 ],
12 "stream": True,
13 "max_tokens": 1024
14 },
15 stream=True
16)
17
18for line in response.iter_lines():
19 if line:
20 print(line.decode("utf-8"))
```
### JavaScript — Function Calling
javascript
```
1const response = await fetch("https://modelslab.com/api/v6/llm/chat", {
2 method: "POST",
3 headers: { "Content-Type": "application/json" },
4 body: JSON.stringify({
5 key: "your_api_key",
6 model_id: "qwen-2.5-72b",
7 messages: [
8 { role: "user", content: "What's the weather in San Francisco?" }
9 ],
10 tools: [{
11 type: "function",
12 function: {
13 name: "get_weather",
14 description: "Get current weather for a location",
15 parameters: {
16 type: "object",
17 properties: {
18 location: { type: "string", description: "City name" }
19 },
20 required: ["location"]
21 }
22 }
23 }]
24 })
25});
26
27const data = await response.json();
28console.log(data);
```
What LLM Models Can You Access?
---
Access multiple LLM models through a single API endpoint. Deploy chatbots with streaming responses, context management, and custom system prompts.
Multiple LLM Models Choose from a range of open-source large language models including Llama 3.1, Mistral, DeepSeek R1, and specialized fine-tuned variants. Switch models with a single parameter change — no infrastructure changes needed.
Streaming Responses Deliver real-time, token-by-token responses to your users with server-sent events. Reduce perceived latency and create responsive chat experiences that feel natural.
Custom System Prompts Define your chatbot personality, tone, and behavior with system prompts. Create specialized assistants for customer support, sales, onboarding, or any domain-specific use case.
Chat Options Access models without content restrictions for creative writing, roleplay, fiction, and research applications. Full control over content filtering at the API level.
Everything you need to build production-ready chatbots and conversational AI applications.
[Start Free Trial](https://modelslab.com/register)
How to Build a Chatbot with Our API
---
Deploy your first AI chatbot in minutes, not weeks.
STEP 01
STEP 01
### Step 1: Get Your API Key
Create a free account on ModelsLab and generate your chatbot API key from the dashboard. Start with the free tier — no credit card required.
STEP 02
STEP 02
### Step 2: Configure Your Chatbot
Choose your LLM model, set a system prompt to define your chatbot personality, and configure parameters like temperature, max tokens, and response format.
STEP 03
STEP 03
### Step 3: Integrate and Deploy
Send chat messages via our REST API or use our Python/JavaScript SDK. Handle streaming responses and build conversational flows in your application.
[Get Your API Key ](https://modelslab.com/register)
Why Build Chatbots with ModelsLab?
---
Key advantages that set us apart
Access to Llama 3.1, Mistral, DeepSeek R1, and other open-source LLMs
Streaming responses with server-sent events
Custom system prompts for chatbot personality
Open-source model options with flexible content policies
Conversation context management built in
JSON mode for structured data extraction
Function calling support for tool use
OpenAI-compatible API format for easy migration
Sub-second first-token latency
Pay-per-token pricing starting at $1.50/M tokens
Python and JavaScript SDKs available
24/7 developer support via Discord
GDPR-compliant data handling
No questions asked refund policy
Our Popular Use Cases
Use cases for our chatbot API:
Customer SupportContent GenerationVirtual AssistantsEducation and TutoringHealthcare TriageSales and Lead Qualification
Automate support tickets with AI chatbots that understand context, resolve common issues, and escalate complex cases to human agents.
Your Data is Secure: GDPR Compliant AI Services
---
AI Image API Pricing Starting at $0.0047 Per Image
---
ModelsLab offers a free tier with pay-as-you-go pricing, a Standard plan at $47/month for 10,000 API calls, and a Premium plan at $199/month with unlimited calls. All plans include access to Flux, SDXL, Stable Diffusion 3, and 10,000+ community models. Cancel anytime.
Coming Soon
---
We are making some changes to our pricing, please check back later.
Chatbot API — Frequently Asked Questions
---
### What LLM models are available through the ModelsLab Chatbot API?
ModelsLab provides access to Llama 3.1 (8B, 70B, 405B), Mistral, DeepSeek R1, DeepSeek V3, Qwen 2.5 (7B, 32B, 72B), and dozens of other open-source and fine-tuned LLM models. You can switch between models by changing the model\_id parameter in your API request.
### How much does the Chatbot API cost?
Pricing is pay-per-token with no minimums. DeepSeek R1 costs $2.40 per million tokens, Qwen models range from $2.00 to $3.60 per million tokens, and Llama models start at $1.50 per million tokens. A free tier is available with limited usage — no credit card required.
### Is the API compatible with OpenAI format?
Yes, the ModelsLab Chatbot API follows the OpenAI chat completions format. Existing code built for OpenAI can migrate by changing the base URL and API key. This includes streaming, function calling, JSON mode, and conversation history management.
### Does the API support streaming responses?
Yes, the API supports real-time streaming via server-sent events (SSE). Set stream: true in your request to receive token-by-token responses, reducing perceived latency for chat applications.
### What is the response latency?
First-token latency is typically under 1 second for most models. Total generation time depends on the model size and max\_tokens parameter. Streaming mode delivers tokens in real-time as they are generated.
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---
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---
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---
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---
*Generated by ModelsLab - 2026-04-06*