Anthropic

Every Claude model — Opus, Sonnet, and Haiku across the 3.5, 4, 4.5, 4.6, 4.7, and 4.8 generations — is routable through Verlon with your existing Anthropic SDK unchanged. Just point baseURL at Verlon and swap the API key.

Chat models

Model ID	Type	Context
`claude-fable-5`	chat	1000K
`claude-haiku-4-5-20251001`	chat	200K
`claude-opus-4-5`	chat	—
`claude-opus-4-5-20251101`	chat	200K
`claude-opus-4-6`	chat	1000K
`claude-opus-4-7`	chat	1000K
`claude-opus-4-8`	chat	1000K
`claude-opus-5`	chat	1000K
`claude-sonnet-4-5-20250929`	chat	1000K
`claude-sonnet-4-6`	chat	1000K
`claude-sonnet-5`	chat	1000K

This table is auto-generated from the Verlon model registry on every sync — see the live registry for pricing, benchmarks, and deprecation dates.

Other modalities

No non-chat models.

Quickstart

First time? Create a gate and grab an API key — the examples below need a GATE_ID and VERLON_API_KEY.

The fastest path — Verlon SDK, one call:

import { Verlon } from '@verlon-ai/sdk';

const verlon = new Verlon({ apiKey: process.env.VERLON_API_KEY });

const response = await verlon.chat({
  gateId: process.env.GATE_ID,
  model: 'claude-sonnet-4-6', // optional — overrides the gate's configured model
  data: {
    messages: [{ role: 'user', content: 'Hello!' }],
  },
});

console.log(response.content);

Any chat model from the table above works — swap claude-sonnet-4-6 for claude-opus-4-8, claude-haiku-4-5-20251001, or any other ID.

SDK compatibility

Verlon exposes an Anthropic-compatible endpoint. The official Anthropic SDK works unchanged — swap two lines and every model in the table above becomes callable through the SDK you already know.

Configuration — just two lines

import Anthropic from '@anthropic-ai/sdk';

const anthropic = new Anthropic({
  apiKey: process.env.ANTHROPIC_API_KEY,
});

import Anthropic from '@anthropic-ai/sdk';

const anthropic = new Anthropic({
  baseURL: 'https://api.verlon.ai', // ← add this
  apiKey: process.env.VERLON_API_KEY, // ← change this
});

Specifying your gate

Verlon supports three ways to point a request at a gate:

Using gateId (Recommended)
Using model field
Using a default header

// @ts-ignore - gateId is a Verlon AI extension
const response = await anthropic.messages.create({
  gateId: process.env.GATE_ID,
  max_tokens: 1024,
  messages: [{ role: 'user', content: 'Hello!' }],
});

Requires @ts-ignore in TypeScript, but the clearest intent.

const response = await anthropic.messages.create({
  model: process.env.GATE_ID, // gate UUID in the model slot
  max_tokens: 1024,
  messages: [{ role: 'user', content: 'Hello!' }],
});

No TypeScript errors, drop-in with existing code.

const anthropic = new Anthropic({
  baseURL: 'https://api.verlon.ai',
  apiKey: process.env.VERLON_API_KEY,
  defaultHeaders: { 'X-Verlon-Gate-Id': process.env.GATE_ID },
});

const response = await anthropic.messages.create({
  max_tokens: 1024,
  messages: [{ role: 'user', content: 'Hello!' }],
});

Cleanest for TypeScript — set once, use everywhere.

Streaming

Identical behavior to the Anthropic SDK — stream: true returns an async iterable of MessageStreamEvent objects.

const stream = await anthropic.messages.create({
  gateId: process.env.GATE_ID,
  max_tokens: 1024,
  messages: [{ role: 'user', content: 'Tell me a joke.' }],
  stream: true,
});

for await (const event of stream) {
  if (event.type === 'content_block_delta' && event.delta.type === 'text_delta') {
    process.stdout.write(event.delta.text);
  }
}

Language coverage

import Anthropic from '@anthropic-ai/sdk';

const anthropic = new Anthropic({
  baseURL: 'https://api.verlon.ai',
  apiKey: process.env.VERLON_API_KEY,
});

const response = await anthropic.messages.create({
  gateId: process.env.GATE_ID,
  max_tokens: 1024,
  messages: [{ role: 'user', content: 'Hello!' }],
});

console.log(response.content[0].text);

from anthropic import Anthropic

client = Anthropic(
    base_url="https://api.verlon.ai",
    api_key=os.environ["VERLON_API_KEY"],
)

response = client.messages.create(
    model=os.environ["GATE_ID"],
    max_tokens=1024,
    messages=[{"role": "user", "content": "Hello!"}],
)

print(response.content[0].text)

curl https://api.verlon.ai/v1/messages \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer $VERLON_API_KEY" \
  -H "anthropic-version: 2023-06-01" \
  -d '{
    "gateId": "'"$GATE_ID"'",
    "max_tokens": 1024,
    "messages": [{"role": "user", "content": "Hello!"}]
  }'

What’s supported

Streaming

Full support for stream: true, identical semantics to Anthropic’s SDK.

Tool use

Fully supported. Verlon translates across providers if your gate routes to a non-Claude model.

Vision

Image inputs in messages work with any vision-capable model.

System messages + all message types

System prompts, user, assistant, and tool_result blocks all pass through.

Standard parameters

temperature, max_tokens, top_p, top_k, stop_sequences, and the rest — all passed through.

Usage + cost tracking

Standard response.usage with token counts, plus Verlon’s cost field with per-call dollar amount.

Migrating an existing Anthropic app

Update client initialization

Swap baseURL + apiKey. Two lines.

Add a gate reference

Pass gateId (or set the default header). max_tokens, messages, and everything else stay the same.

Test in development

Verify requests appear in the Verlon dashboard and cost tracking works.

Deploy

Ship. If anything breaks, revert the two-line diff — takes 30 seconds.

How it works

You send an Anthropic-format request to https://api.verlon.ai/v1/messages
Verlon receives — validates the gate, applies routing rules
Verlon routes to whichever model your gate points at (Claude, GPT, Gemini, Mistral, or anything else in the registry)
The provider responds in its native format
Verlon normalizes back to Anthropic format
You receive a standard Anthropic response with an added cost field

Your code doesn’t know the difference.

Errors

Errors come back Anthropic-shaped — { "type": "error", "error": { "type", "message" } } — so the Anthropic SDK’s error classes work unchanged.

Status	Meaning	What to check
`400`	Invalid request	Malformed body or missing `gateId`
`401`	Invalid API key	Your `VERLON_API_KEY` value and the `Authorization: Bearer` header
`404`	Gate not found	Your `GATE_ID` — the error message names the offending ID
`429`	Rate limit exceeded	Back off and retry; the body includes `reset_at`, and every response carries `X-RateLimit-*` headers

try {
  const response = await anthropic.messages.create({
    gateId: process.env.GATE_ID,
    max_tokens: 1024,
    messages: [{ role: 'user', content: 'Hello!' }],
  });
} catch (error) {
  if (error.status === 404) {
    console.error('Gate not found — check GATE_ID');
  } else if (error.status === 429) {
    console.error('Rate limited — retry after the reset');
  } else {
    throw error;
  }
}

FAQ

Do I need to change my request code?

No. Change baseURL + apiKey in the client. The messages.create calls stay identical.

Can I still call Anthropic directly?

Yes. Revert baseURL + apiKey to Anthropic values and you’re back on their API.

Can I route a GPT or Gemini model through the Anthropic SDK?

Yes — that’s the point. Configure your gate to route to any model in the registry and your Anthropic SDK code stays the same.

Do I need the Verlon SDK?

No. This whole guide uses only the Anthropic SDK.

Full non-chat model list

This provider is chat-only — see the table above.

OpenAI · Google · Mistral
Verlon SDK reference — full-feature native SDK for new projects
Gates — set up routing rules and model configuration
Bring your own key — use your own Anthropic account for provider costs
Anthropic’s official docs ↗

Getting Started

SDK Reference

Platform

Integrations

Provider Compatibility

Chat models

Other modalities

Quickstart

SDK compatibility

Configuration — just two lines

Specifying your gate

Streaming

Language coverage

What’s supported

Migrating an existing Anthropic app

How it works

Errors

FAQ

Full non-chat model list

​Chat models

​Other modalities

​Quickstart

​SDK compatibility

​Configuration — just two lines

​Specifying your gate

​Streaming

​Language coverage

​What’s supported

​Migrating an existing Anthropic app

​How it works

​Errors

​FAQ

​Full non-chat model list

​Related

Chat models

Other modalities

Quickstart

SDK compatibility

Configuration — just two lines

Specifying your gate

Streaming

Language coverage

What’s supported

Migrating an existing Anthropic app

How it works

Errors

FAQ

Full non-chat model list

Related