deploybase

LLM API Gateway: Build vs Buy Comparison

Deploybase · June 24, 2025 · AI Infrastructure

Contents

What is an LLM API Gateway

One interface to many models. Handles auth, rate limiting, routing, cost tracking.

Switch providers without rewriting code. Use OpenAI one day, Anthropic the next. Same client code.

Core functionality includes:

  • Provider abstraction (unified API format)
  • Request routing and load balancing
  • Token counting and cost attribution
  • Rate limiting and quota management
  • Request logging and analytics
  • Fallback mechanisms for reliability

Buy Options Review

Hosted Solutions

LiteLLM Cloud: Hosted version of the LiteLLM open-source gateway, providing managed deployment with built-in provider support. Pricing starts at $0.05 per 1M tokens routed plus fixed monthly fee.

Amazon Bedrock: AWS-managed service aggregating multiple models from Anthropic, Meta, Mistral, and others. Pricing passes through provider costs with 15-25% markup.

Replicate Gateway: Simplified proxy for open-source models with built-in caching.

Together AI: Managed platform routing to open-source and proprietary models.

These solutions require minimal infrastructure. Monthly costs range from $100-1,000 depending on token volume.

Self-Hosted Open Source

LiteLLM Server: Self-host LiteLLM gateway component. Deploy on Kubernetes or traditional servers.

Outlines: Lightweight Python gateway focusing on structured outputs.

llama.cpp: C++ inference engine that can serve models via a built-in HTTP API endpoint, usable as a lightweight self-hosted backend.

Self-hosted options reduce variable costs to hardware only. Initial setup requires 2-4 engineering weeks.

Build Approach Analysis

Building custom gateways provides maximum control and optimization opportunities.

Advantages

Custom Optimization: Implement provider-specific optimizations. Route slower requests to faster providers. Implement smart fallbacks based on latency.

Cost Control: Direct provider relationships allow volume discounts. No SaaS markup applied.

Feature Customization: Build domain-specific functionality (specialized caching, prompt optimization, output validation).

Compliance Requirements: Keep all data within internal systems for regulated industries.

No Vendor Lock-in: Change providers without platform constraints.

Disadvantages

Development Cost: Initial build requires 6-12 engineering weeks. Estimate 2-3 engineers at $150-250/hour.

Maintenance Burden: Ongoing updates, monitoring, and debugging consume engineering resources.

Complexity Management: Multi-provider support adds operational complexity.

Scalability Challenges: Building for global scale requires additional infrastructure.

Security Responsibility: Complete responsibility for API security, authentication, and data protection.

Cost Comparison

Buy Scenario (Hosted)

LiteLLM SaaS: 1B tokens monthly at $50K/month provider costs

  • LiteLLM fee: $0.05 per 1M tokens = $50
  • Fixed monthly fee: $500
  • Total: $50,550/month
  • Annual: $606,600

Amazon Bedrock: Same 1B tokens at $50K/month provider costs

  • Bedrock markup: 20% = $10,000
  • Total: $60,000/month
  • Annual: $720,000

Build Scenario

Initial Development: 3 engineers at $200/hour for 10 weeks

  • Engineering cost: 3 × 40 hours/week × 10 weeks × $200 = $240,000
  • Infrastructure setup: $5,000
  • Total initial: $245,000

Ongoing Operations: 1 full-time engineer for maintenance

  • Annual cost: $200,000
  • Infrastructure: $5,000/month = $60,000/year
  • Total annual: $260,000

Multi-Year Comparison:

  • Year 1: $245,000 build + $260,000 ops = $505,000
  • Year 2-3: $260,000/year operations only

Build approach achieves cost parity with SaaS by month 18-24. Teams operating gateways 3+ years benefit from building.

Feature Matrix

FeatureLiteLLMBedrockSelf-Hosted
Multi-provider routingYesLimitedYes
Custom authLimitedAWS IAMFull control
Provider fallbackYesNoCustom
Rate limitingYesYesCustom
Request cachingYesLimitedCustom
Cost trackingYesYesCustom
Compliance readyNoAWS complianceYes
Downtime SLA99.5%99.99%Self-managed
Setup timeMinutesHoursWeeks
Monthly cost (1B tokens)$550$10,000$5,000

Implementation Considerations

Choosing Buy

Teams should consider hosted solutions when:

  • Token volume under 500B monthly
  • Compliance requirements minimal
  • Team lacks infrastructure expertise
  • Rapid deployment critical

Choosing Build

Build when:

  • Token volume exceeds 1B monthly
  • Custom routing logic valuable
  • Compliance demands internal control
  • Cost optimization critical
  • Multi-year timeline

Hybrid Approach

Start with hosted solution for 6-12 months gathering requirements. Build custom gateway once patterns emerge and volume justifies engineering investment.

Many teams use self-hosted LLM for some services while maintaining documentation and standards. Compare compliance options using secure compliant LLM hosting in the cloud.

FAQ

How many tokens pass through typical gateways? SaaS gateways typically handle 100M-10B tokens monthly. Self-hosted deployments range from 1B-100B tokens monthly depending on organization size.

What's the latency overhead of API gateways? Well-implemented gateways add 20-100ms latency. LiteLLM adds approximately 50ms. Bedrock adds 100-200ms. Custom gateways optimized for latency achieve 20-50ms overhead.

Can gateways cache responses? Yes. Semantic caching identifies similar requests and reuses prior responses. Token savings reach 30-50% on typical workloads.

What happens if a provider becomes unavailable? Quality gateways implement provider fallback. Requests route to backup providers automatically. Fallback latency typically increases 50-100ms.

Do gateways work with fine-tuned models? Yes. Fine-tuned models route through gateways like standard APIs. Some platforms charge premium rates for custom model serving.

How much engineering effort maintains a gateway? Full-time engineer can manage gateways handling up to 10B tokens monthly. Beyond that, teams expand to 2-3 engineers.

Explore self-hosting fundamentals through self-hosted LLM documentation. Consider compliance requirements in secure compliant LLM hosting cloud.

Understand underlying infrastructure costs through GPU pricing guide for compute requirements.

Sources