---
title: "SDK and CLI: connect an app, read it live | OpsOptic"
description: "Adapters for Hono, Express, Next.js and Bun, plus Python and Go ports, and an optic CLI that tails events and logs. What each one sends and how it delivers."
image: "https://opsoptic.com/og-image.png"
---

# Connect an app with the SDK, read it from the terminal

No agent to run. A small client library in your app sends events and logs over HTTP, and the optic CLI reads them back.

[Talk to the founder on WhatsApp](https://wa.me/5548992091242?text=Hi!%20I%20saw%20the%20OpsOptic%20site%20and%20I%20would%20like%20to%20talk%20about%20early%20access.%20%28from%3A%20sdk%20top%29)

**Not published yet.** The SDK and CLI packages are not on npm, PyPI or a Go module proxy, so this page shows no install command. Early access includes them.

## Adapters

The core client has no runtime dependencies. Each adapter records every request as an event with its method, path, status code and latency.

| Runtime | Entry point | Notes |
| --- | --- | --- |
| Hono | `@opsoptic/sdk/hono` | Middleware for every route you register it before. |
| Express | `@opsoptic/sdk/express` | Middleware. |
| Next.js | `@opsoptic/sdk/next` | Runs in `middleware.ts`. It cannot see the final response status, so requests are recorded as 200. |
| Bun.serve() | `@opsoptic/sdk/bun` | Wraps your fetch handler. |
| Python | `opsoptic` | ASGI middleware, Django and Flask entry points, and a logging handler. |
| Go | Go module | net/http middleware and a `slog` handler. |

Any other runtime can send events by hand through the core client.

## What you can send

core client

```
const optic = init({ apiKey: process.env.OPSOPTIC_KEY! })

optic.identify('user-1', { plan: 'pro' })
optic.track('checkout.started', { plan: 'pro' })
// amount is in the minor unit: 2900 is 29.00 USD
optic.revenue('subscription.created', { amount: 2900, currency: 'USD' })
optic.captureError(err)
```

The client also has a logger with `debug`, `info`, `warn` and `error` methods, and `stripeRevenue(event)`, which turns a Stripe webhook event you have already verified into a revenue event.

## Delivery behavior

**Batching**

Events are queued and flushed every 5 seconds, up to 100 per batch, by default.

**Retries**

A failed flush makes 3 attempts in total, waiting 1 second and then 4 seconds, then requeues the batch for the next cycle.

**Backpressure**

The queue holds up to 1,000 events by default. When it overflows, the oldest events are dropped first.

**Sampling**

`sampleRate` thins request and custom events only. Errors, revenue and identify events are never sampled away.

**Rejections**

A rejected key or oversized batch is reported through `onIngestError`, by default as one console warning that is not repeated for 5 minutes.

**Limits**

One ingest request carries at most 10,000 events or 8 MiB, whichever comes first.

## The CLI

The `optic` command compiles to a standalone binary. Credentials are kept in `~/.optic` with restricted permissions, and `--profile <name>` switches between named workspaces. Most commands accept `--json`.

**`optic status`**

Live stats for every project.

**`optic tail [project]`**

Streams events and logs. Filter with `--filter level=error`, `status=500`, `type=ERROR` or `path=/api/checkout`.

**`optic watch [project]`**

Live events with stats, refreshed every few seconds.

**`optic stats [project] [period]`**

Summary for MINUTE, HOUR, DAY or WEEK.

**`optic errors [project]`**

Recent error log.

**`optic users [project] [free|paid]`**

Tracked users, optionally by plan.

**`optic deploy <project>`**

Records a deployment, with `--commit <sha>`.

**`optic key create|rotate|revoke`**

Manages SDK keys. The raw key is shown only in human output.

**`optic alerts list`, `optic backtest`**

List alert rules, or test a condition against historical data.

**`optic incidents open|list`**

Open or list incidents.

**`optic cohorts`**

Revenue cohort retention.

Want the client packages for a product of yours? Early access starts with a conversation.

[Talk to the founder on WhatsApp](https://wa.me/5548992091242?text=Hi!%20I%20saw%20the%20OpsOptic%20site%20and%20I%20would%20like%20to%20talk%20about%20early%20access.%20%28from%3A%20sdk%20page%29)