Nozle Python SDK

Feature Event writes use the Go Engine at https://api.nozle.app/engine/api/v1/events (batch: /events/batch). Configure base_url for a custom ingestion endpoint. events_url configures Core billing resources and subscription discovery.

Backend-only Python SDK for Nozle billing, exact-decimal credits, Entity lifecycle, ledger usage, margin intelligence, and LLM usage capture.

Install

pip install nozle-sdk==0.10.0

Python 3.9 through 3.13 are supported. The package is typed and includes py.typed.

Version 0.9.1 converts RFC 3339 Feature Event timestamps to the Unix-second format Core accepts, including events created by the OpenAI and Anthropic wrappers. See the changelog.

Authentication

• pk_ publishable keys may call only plans().
• sk_ secret keys are required for every customer read, mutation, event, credit, Entity, usage, and margin operation.
• Protected operations reject pk_ locally before network I/O.

Keep secret keys on a trusted backend. This package is not a browser SDK. When a request originates in a browser, authenticate it in your backend and derive the Nozle customer_id from that authenticated user, team, or organization. Do not treat a browser-supplied customer ID as authoritative.

from nozle import Nozle

nozle = Nozle(
    api_key="sk_backend_...",
    base_url="https://api.nozle.app/engine",
    events_url="https://api.nozle.app/core",
    timeout=15,
)

Public namespaces

The client exposes events, cost_events, customers, credit_systems, credits, entities, usage, and margin.

Plans and checkout

plans = nozle.plans()

checkout = nozle.checkout(
    "customer-123",
    "pro",
    return_url="https://merchant.example/billing/complete",
)

Checkout can return any production transition shape:

• {"type": "stripe", "client_secret": "cs_..."}: Stripe embedded Checkout Session
• {"type": "razorpay", "key_id": "...", "order_id": "..."}: Razorpay order for the modal
• {"type": "hosted", "payment_url": "https://..."}: declared in the result types; POST /checkout does not return it for Razorpay (invoice payment URLs and credit top-ups return a payment_url with no checkout id to poll)
• {"type": "processing", "checkout_id": "...", "status": "..."}: Razorpay order not ready, or a Stripe quoted upgrade replayed while its webhook is pending
• {"type": "completed", "status": "..."}
• {"type": "scheduled", "status": "..."}

See Payment providers for what to do with each.

The deprecated success_url= argument remains an alias for return_url=. The SDK never sends both fields and rejects conflicting values.

Backend subscription creation remains available with nozle.subscribe(customer_id, plan_code). Both checkout and subscription creation require an sk_ key.

Cancellation is also backend-only. It defaults to end-of-period behavior, preserving access until Nozle's authoritative billing boundary:

result = nozle.cancel_subscription("customer-123", "subscription-123")
# result["subscription"]["status"] == "active"
# result["subscription"]["ending_at"] contains the scheduled boundary

Immediate termination must be explicit:

nozle.cancel_subscription("customer-123", "subscription-123", policy="immediate")

Create one payment for a mixed basket of Entity plans:

checkout = nozle.entity_subscriptions.checkout_many(
    "workspace_123",
    billing_time="anniversary",
    return_url="https://app.example.com/settings/billing",
    idempotency_key="workspace-123-seat-purchase-v1",
    items=[
        {"external_entity_id": "seat_pro_001", "plan_code": "pro_monthly"},
        {"external_entity_id": "seat_max_001", "plan_code": "max_monthly"},
    ],
)

Return the checkout result to the authenticated frontend and mount checkout["client_secret"] using @nozle-js/react. Never expose the secret key.

Customers and Credit Systems

Customer writes go directly to Nozle Core using the merchant's secret key, so Core derives the owning organization from that key.

customer = nozle.customers.upsert(
    "customer-123",
    name="Acme",
    email="billing@example.com",
)

# Link a customer that already exists in Stripe, without creating a new one.
# A provider assignment needs provider_customer_id or sync_with_provider=True.
nozle.customers.upsert(
    "customer-123",
    billing_configuration={
        "payment_provider": "stripe",
        "payment_provider_code": "stripe_main",
        "provider_customer_id": "cus_ABC123",
    },
)

# Follows every active Core page and returns one normalized list.
systems = nozle.credit_systems.list()

If you create customers through the Nozle REST API instead of this SDK, a customer needs sync_with_provider: true or a provider_customer_id; otherwise its payment provider assignment is dropped.

Customer and Entity credits

balance = nozle.credits.get_balance("customer-123", "ai_credits")
balances = nozle.credits.list_balances("customer-123")
operations = nozle.credits.list_operations(
    "customer-123",
    credit_system_code="ai_credits",
    limit=50,
    cursor=None,
)

entity_balance = nozle.credits.get_entity_balance(
    "customer-123", "user-42", "ai_credits"
)
entity_balances = nozle.credits.list_entity_balances("customer-123", "user-42")
entity_operations = nozle.credits.list_entity_operations(
    "customer-123", "user-42", limit=50
)

allocation = nozle.credits.allocate(
    "customer-123",
    "user-42",
    credit_system_code="ai_credits",
    amount="100.000000000001",
    idempotency_key="allocation-user-42-v1",
)

Every credit amount is returned as a string and is never converted to float. Allocation and deallocation amounts must be positive decimal strings with at most 12 decimal places. Mutation idempotency keys are mandatory and must fit within 255 UTF-8 bytes.

Entities

entity = nozle.entities.get("customer-123", "user-42")
page = nozle.entities.list("customer-123", status="active", limit=50)

result = nozle.entities.upsert(
    "customer-123",
    "user-42",
    status="active",
    name="Asha",
    metadata={"team": "support"},
    idempotency_key="entity-user-42-v1",
)

nozle.entities.suspend(
    "customer-123", "user-42", idempotency_key="suspend-user-42-v1"
)
nozle.entities.activate(
    "customer-123", "user-42", idempotency_key="activate-user-42-v1"
)

nozle.entities.bulk_upsert(
    "customer-123",
    [
        {"external_id": "user-42", "status": "active"},
        {"external_id": "user-43", "status": "suspended"},
    ],
    idempotency_key="entity-import-v1",
)

Entity IDs use UTF-8 byte limits, list limits are 1–100, and bulk upserts accept 1–500 unique Entity IDs.

Ledger usage

usage.check() is advisory and does not mutate a balance. usage.track() atomically records consumption and requires an idempotency key.

preview = nozle.usage.check(
    "customer-123",
    "agent_execution",
    entity_id="user-42",
    credit_system_code="ai_credits",
    properties={"model": "gpt-5"},
    occurred_at="2026-07-20T12:00:00.750Z",
)

consumption = nozle.usage.track(
    "customer-123",
    "agent_execution",
    entity_id="user-42",
    properties={"model": "gpt-5"},
    timestamp="2026-07-20T12:00:00.750Z",
    idempotency_key="execution-123",
)

The SDK does not automatically retry mutation requests. Retry only with the same idempotency key after deciding the failure is safe to retry.

Existing operations

transaction_id = nozle.track(
    "customer-123",
    "copilot_action",
    metadata={"mode": "planning"},
    subscription_id="subscription-123",
)

nozle.cost_events.track(
    cost_meter_code="ai_tokens",
    parent_transaction_id=transaction_id,
    request_id="provider-request-123",
    operation_key="planning",
    properties={"model": "gpt-5", "type": "output", "tokens": 900},
)

entitlement = nozle.can("customer-123", "code_completion")
deduction = nozle.check_and_deduct("customer-123", credits=5)  # legacy wallet adapter; `feature` is deprecated and ignored
health = nozle.ping()

summary = nozle.margin.summary()
by_customer = nozle.margin.by_customer()
trend = nozle.margin.trend(granularity="week")

If track() is called without subscription_id, the SDK resolves and caches the customer's single active subscription through Core. subscribe(), checkout(), cancel_subscription() and apply_subscription_transition() clear that cache for the customer. A change made elsewhere needs an explicit subscription_id. track() returns the organization-wide transaction_id; when none is supplied, the SDK generates a UUID version 7 identifier before sending the request. This lets a Cost Event reference the Feature Event without waiting for a server response, and out-of-order delivery remains safe.

You can generate both identifiers explicitly when coordinating asynchronous work:

transaction_id = nozle.events.create_transaction_id()
cost_event_id = nozle.cost_events.create_cost_event_id()

nozle.track(
    "customer-123",
    "copilot_action",
    subscription_id="subscription-123",
    transaction_id=transaction_id,
)

nozle.cost_events.track(
    cost_event_id=cost_event_id,
    cost_meter_code="ai_tokens",
    parent_transaction_id=transaction_id,
    properties={"model": "gpt-5", "type": "input", "tokens": 150},
)

For a cost attributable to a customer but not one Feature Event, provide external_customer_id instead of parent_transaction_id. Cost Event methods require a secret key.

OpenAI and Anthropic wrappers

Install an optional provider dependency:

pip install "nozle-sdk[openai]"
pip install "nozle-sdk[anthropic]"

from openai import OpenAI
from nozle import Nozle, wrap_openai

nozle = Nozle("sk_backend_...")
openai = wrap_openai(
    OpenAI(),
    nozle,
    customer_id="customer-123",
    metric_code="llm_tokens",
    cost_meter_code="ai_tokens",
    feature="assistant",
)

response = openai.chat.completions.create(
    model="gpt-5",
    messages=[{"role": "user", "content": "Hello"}],
)

Synchronous clients, asynchronous clients, synchronous streams, and asynchronous streams are supported for OpenAI and Anthropic. The parent Feature Event contains:

• model
• provider
• input_tokens
• output_tokens
• latency_ms
• optional feature

When cost_meter_code is set, the wrapper generates the parent transaction_id before delivery and emits one linked Cost Event for each non-zero token category. The canonical Cost Event properties are tokens, provider, model, and type. OpenAI supports input, cached_input, output, and reasoning; Anthropic supports input, cached_input, cache_write, and output. Parent and child events may arrive out of order safely.

Provider failures are propagated. If the provider succeeds but Nozle tracking fails, the successful provider response or completed stream is preserved and a NozleTrackingWarning is emitted without credential-bearing error details.

Errors

NozleAPIError exposes operation, status_code, credential-safe response_details, the top-level code, and has_code() (see Payment providers). Local contract failures use NozleValidationError or NozleAuthenticationError; transport failures use NozleTransportError. Exception messages redact API keys and secret-shaped response fields.

Payment providers: Stripe and Razorpay

checkout() and checkout_invoice() use the payment provider connected to your organization and assigned to the customer, and return a result whose type tells you what to do next. Branch on type; a browser callback alone never proves payment.

Stripe. Plan and invoice checkout always create an embedded Checkout Session. They never return a Stripe-hosted URL or your Stripe publishable key, so the browser needs the pk_ key for the Stripe account connected in Nozle (the React Checkout component takes it as publishableKey). Credit top-up purchases are different: they return a Stripe-hosted payment_url (checkout.stripe.com, valid for 24 hours).

result = nozle.checkout(
    "customer-123",
    "pro_monthly",
    return_url="https://app.example.com/settings/billing",
)
if result["type"] == "stripe":
    # Return the secret to the browser and mount Stripe Embedded Checkout with it.
    client_secret = result.get("client_secret") or result.get("clientSecret")
    # A new subscription has no checkout ID to poll: reload the subscription after
    # Embedded Checkout completes. A paid upgrade carries plan_upgrade_intent_id.

Idempotency keys have two Stripe edge cases today. A new-subscription checkout retried while the subscription is still incomplete fails with HTTP 422 validation_errors containing subscription_incomplete, even with the same key; recover by calling checkout_invoice() with the invoice_id from the first response. An invoice checkout retried with the same key and a different body currently returns HTTP 500, not 409, so keep the body identical for one key.

Razorpay. Razorpay supports only INR. Return the razorpay result to the browser, open the modal there, and post the handler's three fields back to your backend. verify_checkout() sends them to Nozle, which checks the signature and fetches the payment from Razorpay; the SDK does not check the signature locally. Verify and status need an sk_ key.

# Backend: create. The result is {"type": "razorpay", "checkout_id", "key_id", "order_id",
# "amount_cents" (paise), "currency": "INR", "expires_at", "invoice_id" or
# "plan_upgrade_intent_id"}.
checkout = nozle.checkout(
    "customer-123",
    "pro_monthly",
    return_url="https://app.example.com/settings/billing",
    idempotency_key="checkout-customer-123-pro_monthly-v1",
    # register_mandate=True,  # UPI AutoPay: the result also has customer_id,
    #                         # recurring and mandate_max_amount_cents
)
# Invoice-based collection: nozle.checkout_invoice(invoice_id, idempotency_key=attempt_id)

# Browser (after loading https://checkout.razorpay.com/v1/checkout.js):
#   new Razorpay({key: key_id, order_id, amount: amount_cents, currency, handler}).open()
# For a mandate also pass customer_id and recurring: "1".

# Backend: verify what the handler returned, then poll until both statuses succeed.
if checkout["type"] == "razorpay":
    status = nozle.verify_checkout(
        checkout["checkout_id"],
        {
            "razorpay_order_id": callback["razorpay_order_id"],
            "razorpay_payment_id": callback["razorpay_payment_id"],
            "razorpay_signature": callback["razorpay_signature"],
        },
        customer_id="customer-123",
        subscription_id="subscription-123",
    )
    status = nozle.checkout_status(
        checkout["checkout_id"],
        customer_id="customer-123",
        subscription_id="subscription-123",
    )
    # status["status"]: awaiting_payment | processing | succeeded | failed | expired | needs_review

Authenticate the buyer and bind each checkout_id to that buyer before forwarding browser callbacks. Pass both scope fields to tie a call to one customer and subscription. Display success only when status and fulfillment_status are both succeeded; a browser callback or a pending debit is not proof that credits or subscriptions are available. Reuse your idempotency key when retrying creation. UPI AutoPay requires merchant enablement and explicit customer authorization; one-time card or UPI payments do not create a mandate.

Provider failures raise NozleAPIError. error.code is the top-level code, and error.has_code() also matches the codes listed in error_details, for example razorpay_requires_inr, payment_provider_required or invalid_checkout_signature.

from nozle import NozleAPIError

try:
    nozle.checkout("customer-123", "pro_monthly", return_url=return_url)
except NozleAPIError as error:
    if error.has_code("razorpay_requires_inr"):
        ...  # price the plan in INR for customers who pay through Razorpay
    else:
        raise

See the Stripe and Razorpay integration guides for connection setup, webhooks, and limits.

React billing portal subscription management

See the runnable authenticated merchant integration for Cancel, Keep, payment-backed upgrades, scheduled downgrades, and exact pending-change withdrawal through the React billing portal. It reuses the existing transition methods and derives customer identity from the merchant session. For end-of-period cancellation, optional expected_effective_at preserves the exact preview timestamp and rejects a changed date atomically on compatible Engine/Core deployments. Existing calls without this option remain compatible.

Version 0.9.0 adds subscription_options(customer_id, subscription_id), preview_subscription_change(customer_id, subscription_id, plan_code), and withdraw_pending_subscription_change(customer_id, subscription_id, pending_subscription_id, idempotency_key=...). Use the existing checkout/transition methods with the selected subscription, signed quote, and a stable action key. Scope checkout_status and verify_checkout with both customer_id and subscription_id. See the method examples.

License

MIT. Versions up to 0.9.1 were published under AGPL-3.0-or-later.