weckr-sdk 0.2.1

AI cost and margin intelligence for SaaS founders

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. The Python counterpart of the TypeScript @weckr/sdk.

Try it live

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

Install

pip install weckr-sdk

Zero runtime dependencies. Bring your own LLM SDK:

pip install weckr-sdk openai            # for OpenAI
pip install weckr-sdk anthropic         # for Anthropic
pip install weckr-sdk google-genai      # for Gemini (new SDK)
# or all at once:
pip install "weckr-sdk[all]"

Quick start

import os
from openai import OpenAI
from weckr import Weckr

openai_client = OpenAI()  # reads OPENAI_API_KEY from env

wk = Weckr(
    api_key=os.environ["WK_API_KEY"],
    plans={"free": 0, "pro": 29, "business": 99},
)

result = wk.chat(
    openai_client,
    {
        "model": "gpt-4o-mini",
        "messages": [{"role": "user", "content": "Summarize this."}],
        "user_id": user.id,
        "feature": "ai-summary",
        "plan": user.plan,
    },
)
print(result.choices[0].message.content)

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 the original result. After it resolves, Weckr fires an async log POST to the Weckr API on a background thread — fire-and-forget, never blocks your request path.

Anthropic

from anthropic import Anthropic
from weckr import Weckr

anthropic_client = Anthropic()
wk = Weckr(api_key=os.environ["WK_API_KEY"], plans={"pro": 29})

msg = wk.chat(
    anthropic_client,
    {
        "model": "claude-sonnet-4",
        "max_tokens": 1024,
        "messages": [{"role": "user", "content": "Hello!"}],
        "user_id": user.id,
        "plan": "pro",
    },
)

Gemini

from google import genai
from weckr import Weckr

genai_client = genai.Client()
wk = Weckr(api_key=os.environ["WK_API_KEY"], plans={"pro": 29})

resp = wk.chat(
    genai_client,
    {
        "model": "gemini-2.5-flash",
        "messages": [{"role": "user", "content": "Hello!"}],
        "user_id": user.id,
        "plan": "pro",
    },
)

Caps + downgrades

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

• action: "block" — wk.chat() raises WeckrCapError and the LLM call is 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.) and emits a one-time WeckrDowngradeWarning per (user, model) pair.

from weckr import Weckr, WeckrCapError, WeckrConfigError

try:
    wk.chat(openai_client, {...})
except WeckrCapError as e:
    show_upgrade_prompt(e.user_id, e.cap)
except WeckrConfigError as e:
    # Typo'd api key, revoked key, or `plan` not in the plans dict —
    # fail-CLOSED so cap enforcement isn't silently disabled.
    alert_backend_team(e.code, str(e))

Short-lived processes (Lambda, cron, CLI)

wk.chat() returns as soon as the LLM call resolves; the log POST runs on a daemon thread. In short-lived processes — Lambda, cron jobs, CLI scripts — call wk.flush() before exit so the daemon thread isn't torn down mid-POST:

wk.chat(openai_client, {...})
wk.flush()      # default 5s timeout

What gets logged

Every successful call (and every failed LLM call) lands in the dashboard:

{
    "userId":         "u_42",
    "feature":        "ai-summary",
    "model":          "gpt-4o-mini",
    "provider":       "openai",
    "inputTokens":    12,
    "outputTokens":   2,
    "costUsd":        0.000003,
    "latencyMs":      1218,
    "planName":       "pro",
    "planRevenueUsd": 29.0,
    "timestamp":      "2026-06-15T07:52:18.086515+00:00",
}

Cost is recomputed server-side from (model, input_tokens, output_tokens) — clients cannot forge cost values. Margin is planRevenueUsd - costUsd (negative means you're losing money on that user); the dashboard derives it on read from SUM(revenue) - SUM(cost) for full precision.

Supported models

• 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.

Dashboard

View cost / margin / per-user / per-feature breakdowns at https://app.useweckr.com/dashboard.

License

MIT