@weckr/sdk

AI cost and margin intelligence for SaaS founders.

See exactly which users cost more than they pay — per LLM call, zero added latency.

Try it live

See the dashboard with real data — no signup needed. 👉 https://app.useweckr.com/demo

Install

npm install @weckr/sdk

Usage

import { Weckr } from '@weckr/sdk';
import OpenAI from 'openai';

const openai = new OpenAI({ apiKey: process.env.OPENAI_API_KEY });

const wk = new Weckr({
  apiKey: 'wk_your_key_here',
  plans: {
    free: 0,
    starter: 9,
    pro: 29,
    business: 99,
  },
});

const result = await wk.chat(openai, {
  model: 'gpt-4o',
  messages: [{ role: 'user', content: prompt }],
  userId: user.id,
  feature: 'ai-summary',
  plan: user.plan,
});

See your own data in the dashboard: https://app.useweckr.com/dashboard Try the demo without signing up: https://app.useweckr.com/demo

The original LLM call runs unchanged and returns immediately. After it resolves, Weckr fires an async log to the Weckr API. The log call is fire-and-forget — if it fails or stalls, your request is unaffected.

Get your API key

Sign up at https://useweckr.com.

Supported providers

• OpenAI — gpt-4o, gpt-4o-mini, gpt-4-turbo, gpt-4, gpt-3.5-turbo, o1-preview, o1-mini
• Anthropic — claude-opus-4, claude-sonnet-4, claude-haiku-4-5, claude-3-5-sonnet, claude-3-5-haiku, claude-3-opus
• Gemini — gemini-2.5-pro, gemini-2.5-flash, gemini-1.5-pro, gemini-1.5-flash

Dated variants (gpt-4o-2024-08-06, claude-3-5-sonnet-latest, …) resolve to the matching family by longest-prefix lookup. Unknown models log costUsd = 0 and don't trigger caps.

Caps + downgrades

Set per-plan spending caps in the dashboard. When a user crosses their cap:

• action: 'block' → wk.chat() throws WeckrCapError (LLM call never made)
• action: 'downgrade' → the SDK silently swaps the model for a cheaper one in the same provider (gpt-4o → gpt-4o-mini, claude-opus-4 → claude-sonnet-4, etc.)

Errors come in two flavors:

import { isWeckrCapError, isWeckrConfigError } from '@weckr/sdk';

try {
  await wk.chat(openai, opts);
} catch (err) {
  if (isWeckrCapError(err))   return showUpgradePrompt(err);
  if (isWeckrConfigError(err)) return logBackendAlert(err); // typo'd api key, unknown plan
  throw err; // real LLM error
}

Short-lived processes (Lambda, cron, CLI)

wk.chat() returns as soon as the LLM call resolves; the log POST is fire-and-forget. In short-lived processes call await wk.flush() before exit to give the POSTs time to land:

await wk.chat(openai, opts);
await wk.flush(); // default 5s timeout

What gets logged

{
  userId, feature, model, provider,
  inputTokens, outputTokens,
  costUsd, latencyMs,
  planName, planRevenueUsd, marginUsd,
  timestamp,
}

Cost is computed from public per-token pricing. Margin is planRevenueUsd - costUsd (negative means you're losing money on that user).

Dashboard

View cost and margin data at https://useweckr.com/dashboard.

License

MIT