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AnnexAPI Review

AnnexAPI is an API tool that intelligently routes requests to the most cost-effective models from various providers, optimizing for price and availability.

shipped Sep 19, 2026paid
AnnexAPI — product screenshot

Why it matters

1Intelligent routing to the most cost-effective AI models.
2Offers 99.9% failover across integrated providers.
3Provides cache-aware billing and metering in USD to five decimal places.
4Supports integrations with OpenAI, Anthropic, Qwen, GLM, Kimi, Grok, DeepSeek, and Gemini.

About AnnexAPI

Business Model
Usage-Based (Pay Per Use)
Usage Pricing
$0.1248 per 1M tokens for Claude Opus per token
Platforms
Web, API
Target Audience
Developers and businesses looking for cost-effective AI model access

Pricing Plans

Pay as you go
  • • No monthly fees
  • • Only pay for what you use

Cost Examples

  • • Claude Opus: $0.1248 per 1M tokens
  • • Claude Sonnet: $0.0832 per 1M tokens
  • • Claude Fable: $11.232 per 1M tokens
  • • GPT 6 Astra: $2.184 per 1M tokens
  • • GLM 5.3: $0.0624 per 1M tokens

Specs

API Available

Yes, public API

overview

What is AnnexAPI?

AnnexAPI is an AI gateway tool that enables developers and businesses to access AI models from various providers with optimized cost and availability. It intelligently routes requests to the most cost-effective models, managing model capacity in volume to ensure efficient resource utilization.

features

Key Features of AnnexAPI

AnnexAPI provides a suite of features designed to optimize AI model access for developers and businesses. Its core functionality revolves around intelligent routing and cost management, ensuring efficient and reliable operation.

  • Intelligent routing to the cheapest AI model providers.
  • 99.9% failover capability across integrated models and providers.
  • Cache-aware billing, optimizing costs by leveraging cached responses.
  • Metering in USD to five decimal places for precise cost tracking.
  • Optimization for both price and availability of AI models.
  • API documentation available at https://annexapi.com/docs.

use cases

Who Should Use AnnexAPI?

AnnexAPI is designed for specific user groups and scenarios where cost-effectiveness and reliability in AI model access are paramount. Its architecture supports various applications requiring optimized AI infrastructure.

  • Developers seeking cost-effective access to a range of AI models without managing individual provider integrations.
  • Businesses aiming to optimize their AI model capacity in volume, reducing operational expenditures.
  • Organizations requiring high availability and failover capabilities for their AI-powered applications.

how to use

How to Use AnnexAPI

To begin using AnnexAPI, users typically integrate its API into their existing applications. The process involves obtaining API access and configuring requests to leverage its intelligent routing capabilities.

  • 1Visit the AnnexAPI website at https://annexapi.com/ to sign up for an account.
  • 2Access the API documentation at https://annexapi.com/docs for integration guidelines.
  • 3Configure your application to send AI model requests through the AnnexAPI endpoint.
  • 4Monitor usage and cost through the provided metering and billing functionalities.
  • 5Leverage intelligent routing to automatically select the most cost-effective and available models for each request.

pricing

AnnexAPI Pricing & Plans

AnnexAPI operates on a usage-based business model, allowing users to pay only for the resources consumed. Specific pricing details are available upon contact with their sales team, with examples provided for various models.

  • Pay as you go: Contact sales for specific pricing.
  • Claude Opus: $0.1248 per 1M tokens.
  • Claude Sonnet: $0.0832 per 1M tokens.
  • Claude Fable: $11.232 per 1M tokens.
  • GPT 6 Astra: $2.184 per 1M tokens.
  • GLM 5.3: $0.0624 per 1M tokens.

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Pros

  • +Intelligent routing automatically selects the most cost-effective AI models.
  • +High availability with 99.9% failover across providers.
  • +Precise cost tracking through metering in USD to five decimal places.
  • +Cache-aware billing reduces overall operational costs.
  • +Simplifies access to multiple AI model providers through a single API.

Cons

  • −As a managed service, it offers less direct control over the underlying gateway compared to self-hosted solutions.
  • −Specific pricing details for the 'Pay as you go' model require contacting sales.
  • −The range of supported models is not explicitly detailed beyond a few examples.
  • −May not offer the same level of deep governance or high-throughput optimization as specialized enterprise gateways.

Similar Tools

AnnexAPI vs Competitors

AnnexAPI competes in the AI gateway and model routing market, offering a managed service focused on cost optimization and availability. Its approach differs from self-hostable solutions and those prioritizing specific enterprise features.

1
LiteLLM↗

Provides a unified OpenAI-compatible API to call over 100 LLM providers, with features like virtual keys, budget limits, and various routing strategies.

LiteLLM offers extensive provider compatibility and self-hosting for full control over your infrastructure, whereas AnnexAPI is a managed service, potentially simplifying setup but offering less direct control over the underlying gateway.

2
Bifrost (Maxim AI)↗

A high-performance, Go-based AI gateway designed for high-throughput production workloads, offering semantic caching and native Model Context Protocol (MCP) support.

Bifrost focuses on high performance and deep governance for enterprise-grade workloads, which might be more robust for complex needs compared to AnnexAPI's more general cost optimization approach.

3
LLM Gateway↗

Offers full self-hosting capabilities with real-time cost and latency analytics, alongside automatic failover across multiple LLM providers.

LLM Gateway provides a fully self-hostable solution with detailed analytics, giving users complete control over their data and infrastructure, unlike AnnexAPI which operates as a hosted service.

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