vexer API

One API key for Claude, Grok and GPT. Fully compatible with the OpenAI and Anthropic APIs, so it drops into the tools you already use — the terminal, your editor, Claude Code, or any SDK. Requests are billed per token against your credit balance; no subscription.

Base URLs

OpenAI-compatible:    https://vexer.chat/v1
Anthropic-compatible: https://vexer.chat   (SDK appends /v1/messages)

Authentication

Create a key at /sign-up (starts with vx-). Send it as Authorization: Bearer vx-… or x-api-key: vx-….

Models

autoRouter — picks a model per request

claude-opus-4-8Anthropic — deepest reasoning

claude-sonnet-5Anthropic — fast, balanced

claude-fable-5Anthropic — creative writing

grok-4.5xAI

gpt-5.6-solOpenAI

OpenAI-compatible — chat completions

curl https://vexer.chat/v1/chat/completions \
  -H "Authorization: Bearer $VEXER_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "claude-sonnet-5",
    "messages": [{"role": "user", "content": "Hello in one sentence."}],
    "stream": false
  }'

OpenAI SDK (Python)

from openai import OpenAI

client = OpenAI(api_key="vx-...", base_url="https://vexer.chat/v1")
resp = client.chat.completions.create(
    model="claude-opus-4-8",
    messages=[{"role": "user", "content": "Explain quantum tunneling briefly."}],
)
print(resp.choices[0].message.content)

OpenAI SDK (JavaScript)

import OpenAI from "openai";

const client = new OpenAI({ apiKey: "vx-...", baseURL: "https://vexer.chat/v1" });
const r = await client.chat.completions.create({
  model: "grok-4.5",
  messages: [{ role: "user", content: "Give me a haiku about the sea." }],
});
console.log(r.choices[0].message.content);

Anthropic-compatible — messages

curl https://vexer.chat/v1/messages \
  -H "x-api-key: $VEXER_KEY" \
  -H "anthropic-version: 2023-06-01" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "claude-opus-4-8",
    "max_tokens": 512,
    "messages": [{"role": "user", "content": "Hi"}]
  }'

Automatic routing & fallback

Pass "model": "auto" to let vexer pick a model per request — hard, long, or code-heavy prompts route to the deepest model, the rest to a fast default. Every model also has a fallback: if the chosen provider is unavailable, the request reroutes before any token streams. The response always reports the model that actually ran (the model field, and the X-Model header on the chat endpoint), so you can see which route handled it. Unknown model ids that look like a known family (e.g. gpt-4o, claude-3-5-haiku) map to the nearest vexer model, so existing clients work unchanged. See the routing guide and the model catalog.

Images (vision)

Send images alongside text on either endpoint. Use a public URL or a base64 data: URI. Vision-capable Claude and GPT models can read them; the vexer chat UI also supports attaching or pasting images.

# OpenAI-compatible — image_url part
curl https://vexer.chat/v1/chat/completions \
  -H "Authorization: Bearer $VEXER_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "claude-opus-4-8",
    "messages": [{"role": "user", "content": [
      {"type": "text", "text": "What is in this image?"},
      {"type": "image_url", "image_url": {"url": "https://example.com/cat.jpg"}}
    ]}]
  }'

# Anthropic-compatible — image source block (base64 or url)
curl https://vexer.chat/v1/messages \
  -H "x-api-key: $VEXER_KEY" \
  -H "anthropic-version: 2023-06-01" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "claude-opus-4-8",
    "max_tokens": 512,
    "messages": [{"role": "user", "content": [
      {"type": "text", "text": "Describe this."},
      {"type": "image", "source": {"type": "url", "url": "https://example.com/cat.jpg"}}
    ]}]
  }'

Claude Code & the Anthropic SDK

Point the Anthropic base URL at vexer and use your vexer key:

export ANTHROPIC_BASE_URL="https://vexer.chat"
export ANTHROPIC_API_KEY="vx-..."
# then run your Anthropic-based tool, e.g.:
claude

Streaming

Set "stream": true. The OpenAI endpoint returns chat.completion.chunk SSE events ending in data: [DONE]; the Anthropic endpoint returns the standard message_start → content_block_delta → message_stop event sequence.

Pricing & limits

Billed per token against your credit balance — top up in the app, no subscription.
Max output: 8192 tokens per request.
Rate limits and a daily spend cap apply per account.
List models any time: GET https://vexer.chat/v1/models.

Get an API key