Forward Proxy & Authentication

This page covers how to authenticate with Lava, construct proxy URLs, and handle responses and errors.

Prerequisites: You need a Lava merchant account with a secret key. See Quickstart: Make Your First Request to get started.

Authentication

Lava supports two ways to authenticate gateway requests:

Method	When to use	Auth header
Secret key	Gateway access without customer billing	`Bearer aks_live_...`
Forward token	Customer billing, metering, or BYOK	`Bearer <base64-encoded JSON>`

Using Your Secret Key (Simplest)

Pass your secret key directly in the Authorization header. Costs are charged to your merchant wallet — no token generation needed.

cURL
SDK

curl -X POST 'https://api.lava.so/v1/forward?u=https%3A%2F%2Fapi.openai.com%2Fv1%2Fchat%2Fcompletions' \
  -H 'Content-Type: application/json' \
  -H "Authorization: Bearer $LAVA_SECRET_KEY" \
  -d '{"model": "gpt-4o-mini", "messages": [{"role": "user", "content": "Hello!"}]}'

import { Lava } from '@lavapayments/nodejs';

const lava = new Lava();

const data = await lava.gateway('https://api.openai.com/v1/chat/completions', {
  body: {
    model: 'gpt-4o-mini',
    messages: [{ role: 'user', content: 'Hello!' }]
  }
});

This is all you need to route requests through the gateway with usage tracking and cost logging.

Forward Tokens

When you need to bill customers, apply metering, or use your own provider keys, use a forward token — a base64-encoded JSON that bundles your secret key with billing parameters.

Token Combinations

The fields you include determine how the request is authenticated and billed:

Combination	Mode	Who pays
`secret_key` only	Gateway	Merchant
`secret_key` + `meter_slug`	Meter-only	Merchant (usage tracked on meter)
`secret_key` + `customer_id` + `meter_slug`	Customer billing	Customer
`secret_key` + `customer_id` + `meter_slug` + `disable_billing`	Billing disabled	Merchant (customer still tracked)

Any combination can include provider_key to use your own provider credentials (BYOK) instead of Lava’s managed keys. disable_billing is only meaningful together with customer_id and meter_slug — it preserves full customer context while redirecting charges to your merchant wallet. Use it for free trials, testing, or promotional requests. See Meter-Only Mode & Disable Billing for details.

Customer Billing Mode

To bill a customer’s wallet, include their customer_id and your pricing meter_slug in the token:

SDK
TypeScript
Python
cURL

import { Lava } from '@lavapayments/nodejs';

const lava = new Lava();

const forwardToken = lava.generateForwardToken({
  customer_id: 'conn_xyz789',    // optional — charges this customer's plan
  meter_slug: 'my-meter',        // optional — prices usage with this meter
  provider_key: 'sk-your-key',   // optional — uses your own provider key (BYOK)
  disable_billing: false,        // optional — when true, tracks usage without charging
});

const tokenData = {
  secret_key: 'aks_live_abc123...',  // your Lava secret key
  customer_id: 'conn_xyz789...',     // optional — charges this customer's plan
  meter_slug: 'my-meter',            // optional — prices usage with this meter
  provider_key: null,                // optional — uses your own provider key (BYOK)
  disable_billing: false,            // optional — when true, tracks usage without charging
};

const forwardToken = btoa(JSON.stringify(tokenData));

import base64, json

token_data = {
    "secret_key": "aks_live_abc123...",  # your Lava secret key
    "customer_id": "conn_xyz789...",     # optional — charges this customer's plan
    "meter_slug": "my-meter",            # optional — prices usage with this meter
    "provider_key": None,                # optional — uses your own provider key (BYOK)
    "disable_billing": False,            # optional — when True, tracks usage without charging
}

forward_token = base64.b64encode(json.dumps(token_data).encode()).decode()

# secret_key: required. All other fields are optional.
# customer_id: charges this customer's plan. meter_slug: prices usage with this meter.
# provider_key: uses your own provider key (BYOK). disable_billing: tracks without charging.
FORWARD_TOKEN=$(echo -n '{"secret_key":"aks_live_abc123...","customer_id":"conn_xyz789...","meter_slug":"my-meter","provider_key":null,"disable_billing":false}' | base64)

Constructing the Request URL

Lava routes requests by wrapping the provider’s API endpoint (e.g., OpenAI’s chat completions URL) as a query parameter using Lava’s forward endpoint:

https://api.lava.so/v1/forward?u=<PROVIDER_URL>

See Supported Providers for the full list of providers you can access with Lava AI Gateway.

As a best practice, the provider URL should be URL-encoded.

Provider Examples

The pattern is the same for every provider — only the URL, body format, and provider-specific headers change.

OpenAI
Anthropic
Google Gemini
SDK

const response = await fetch(
  'https://api.lava.so/v1/forward?u=' +
    encodeURIComponent('https://api.openai.com/v1/chat/completions'),
  {
    method: 'POST',
    headers: {
      'Content-Type': 'application/json',
      'Authorization': `Bearer ${forwardToken}`
    },
    body: JSON.stringify({
      model: 'gpt-4o-mini',
      messages: [{ role: 'user', content: 'Hello!' }]
    })
  }
);

const data = await response.json();
const requestId = response.headers.get('x-lava-request-id');

const response = await fetch(
  'https://api.lava.so/v1/forward?u=' +
    encodeURIComponent('https://api.anthropic.com/v1/messages'),
  {
    method: 'POST',
    headers: {
      'Content-Type': 'application/json',
      'Authorization': `Bearer ${forwardToken}`,
      'anthropic-version': '2023-06-01'  // Required by Anthropic
    },
    body: JSON.stringify({
      model: 'claude-haiku-4-5',
      max_tokens: 1024,
      messages: [{ role: 'user', content: 'Hello!' }]
    })
  }
);

const data = await response.json();
const requestId = response.headers.get('x-lava-request-id');

const response = await fetch(
  'https://api.lava.so/v1/forward?u=' +
    encodeURIComponent('https://generativelanguage.googleapis.com/v1beta/models/gemini-3.5-flash:generateContent'),
  {
    method: 'POST',
    headers: {
      'Content-Type': 'application/json',
      'Authorization': `Bearer ${forwardToken}`
    },
    body: JSON.stringify({
      contents: [{ parts: [{ text: 'Hello!' }] }]
    })
  }
);

const data = await response.json();
const requestId = response.headers.get('x-lava-request-id');

import { Lava } from '@lavapayments/nodejs';

const lava = new Lava();

// OpenAI
const openai = await lava.gateway('https://api.openai.com/v1/chat/completions', {
  body: { model: 'gpt-4o-mini', messages: [{ role: 'user', content: 'Hello!' }] },
  customer_id: 'conn_xyz789',
  meter_slug: 'my-meter',
});

// Anthropic
const anthropic = await lava.gateway('https://api.anthropic.com/v1/messages', {
  body: { model: 'claude-haiku-4-5', max_tokens: 1024, messages: [{ role: 'user', content: 'Hello!' }] },
  headers: { 'anthropic-version': '2023-06-01' },
  customer_id: 'conn_xyz789',
  meter_slug: 'my-meter',
});

// Google Gemini
const gemini = await lava.gateway(
  'https://generativelanguage.googleapis.com/v1beta/models/gemini-3.5-flash:generateContent',
  {
    body: { contents: [{ parts: [{ text: 'Hello!' }] }] },
    customer_id: 'conn_xyz789',
    meter_slug: 'my-meter',
  }
);

Provider-specific headers (like anthropic-version) are passed through unchanged. The request body uses the provider’s native format — Lava doesn’t modify it.

Streaming

Add "stream": true to your request body. Lava proxies SSE chunks in real-time without buffering — the response is identical to calling the provider directly. Usage and billing are recorded after the stream completes.

body: JSON.stringify({
  model: 'gpt-4o-mini',
  messages: [{ role: 'user', content: 'Hello!' }],
  stream: true  // That's it — everything else stays the same
})

Error Handling

Status	Cause	Retryable
401	Invalid secret key or malformed forward token	No — check credentials
402	Insufficient credit balance	No — add funds first
429	Rate limit exceeded	Yes — back off and retry
500/502/503	Provider or Lava server error	Yes — retry with backoff

Provider error responses are forwarded unchanged — check your request body against the provider’s API docs if you see provider-level errors.

Troubleshooting

401 Unauthorized

Verify your secret key matches the dashboard and the Bearer prefix is in the Authorization header. If using a forward token, decode it to inspect:

echo "your_forward_token" | base64 -d

CORS errors in browser

Lava blocks frontend requests to prevent token exposure. Always call Lava from your backend: Frontend → Your Backend → Lava → AI Provider.

Get Started

AI Gateway

AI Spend

Monetize

Integration

SDK

Cookbook

Comparisons

Authentication

Using Your Secret Key (Simplest)

Forward Tokens

Token Combinations

Customer Billing Mode

Constructing the Request URL

Provider Examples

Streaming

Error Handling

Troubleshooting

Next Steps

Supported Providers

Webhooks

​Authentication

​Using Your Secret Key (Simplest)

​Forward Tokens

​Token Combinations

​Customer Billing Mode

​Constructing the Request URL

​Provider Examples

​Streaming

​Error Handling

​Troubleshooting

​Next Steps

Supported Providers

Webhooks

Authentication

Using Your Secret Key (Simplest)

Forward Tokens

Token Combinations

Customer Billing Mode

Constructing the Request URL

Provider Examples

Streaming

Error Handling

Troubleshooting

Next Steps