Bugs reach production. Fixwire finds them first: errors, traces, logs and AI agent runs in one place, an AI debugger on every plan, and your data kept in the region you choose.

Fixwire SDK core for JavaScript

Welcome to @fixwire/core, the runtime-agnostic core of the official JavaScript SDK for Fixwire: the client, scopes, on-device redaction, the crash-loop budget, delivery, tracing and AI agent tracing that every runtime package shares. It is part of the Fixwire SDK for JavaScript, whose README has the full guide.

📦 Getting started

Prerequisites

• A Fixwire account and project: sign up at fixwire.io.
• Node.js 20 or newer, a modern browser or an edge runtime.

Installation

Install the SDK for your runtime instead; it brings this package and re-exports everything here:

| Package | For | |---|---| | @fixwire/node | Node.js: servers, workers, CLIs and serverless functions | | @fixwire/browser | Web apps | | @fixwire/edge | Cloudflare Workers, Vercel Edge, Deno Deploy, Netlify Edge Functions | | @fixwire/react | React, with @fixwire/browser |

npm install @fixwire/node
pnpm add @fixwire/node
yarn add @fixwire/node

Basic configuration

import * as Fixwire from "@fixwire/node"; // or @fixwire/browser, @fixwire/edge

Fixwire.init({
  dsn: "https://<publishable key>@ingest.eu.fixwire.io",
  release: "[email protected]",
  environment: "production",
  tracesSampleRate: 0.2, // record 20% of traces
  // sendDefaultPii: true, // also send users' IP addresses from proxy headers (Node.js)
  // redact: false,        // turn off masking of secrets and personal data
});

The DSN is your project's publishable key and the ingest host, https://<publishable key>@<host>; without one, the SDK does nothing. init() never throws: a broken DSN or option is said in a warning on the console and the SDK stays off.

Quick usage example

Fixwire.captureMessage("Hello Fixwire!"); // an info-level message in your project

try {
  JSON.parse("{ not json");
} catch (err) {
  Fixwire.captureException(err); // the error, with its stack, causes and breadcrumbs
}

✨ Why Fixwire

• Secrets stay on the device. The core masks secrets and personal data with the same rules as the Fixwire server, before anything is sent.
• A crash loop costs a few events, not your quota. Each issue sends a burst of 10 events, then 1 a minute, and a count of the rest.
• It never gets in your app's way. Captures never throw, and queues, strings (1,024 bytes by default), stacks (100 frames) and retries (4 sends) all have fixed limits.
• OpenTelemetry inside. It speaks the Fixwire protocol (OpenTelemetry's OTLP/HTTP plus a few small JSON endpoints).
• Your data stays where you want it. Fixwire keeps it in the region you choose for your project: the EU today, more regions soon.

🧩 Integrations

What the core provides, through every runtime package:

| Integration | What it does | How to use | |---|---|---| | OpenAI | Chat completions, responses and embeddings (streamed too) become spans with the model, tokens and finish reasons | Fixwire.wrapOpenAI(new OpenAI()) | | Anthropic | Messages (streamed too) become chat spans with the model, tokens (cache tokens too) and stop reason | Fixwire.wrapAnthropic(new Anthropic()) | | AI agents | Agent runs, model calls and tool calls with the OpenTelemetry GenAI conventions | Fixwire.ai.agent(), ai.chat(), ai.tool(), ai.embeddings() | | OpenTelemetry | Your OpenTelemetry spans' traces on Fixwire's errors; your OTLP exporters pointed at Fixwire | Fixwire.openTelemetryIntegration(otel), Fixwire.otlpExporterOptions(dsn) | | Custom runtimes | A client without globals, or for a runtime of your own | new Client(options, platform) |

⚙️ Configuration

Every option of init() and new Client() is listed in the repository README.

🧪 Examples

The examples show the runtime packages: an Express API, a worker, a Vite app and an agent on Claude.

📚 Documentation

The full guide lives in the repository README and the examples.

• Configuration
• Examples
• Changelog
• Security policy
• Contributing guide

🚧 Coming from another error tracker?

The API follows the shape most error-tracking SDKs share: init, captureException, captureMessage, setUser, setTag, addBreadcrumb, withScope, withIsolationScope and startSpan. Moving over is mostly a change of package and DSN.

🙌 Want to contribute?

We'd love your help, whether it's a bug report, a fix or a new integration. Start with the contributing guide, then pick from the open issues or the good first issues.

🛟 Need help?

• Questions: ask on Discord or Slack.
• Bugs: open a GitHub issue.
• Found a security issue? Please don't open an issue; follow the security policy.

🔗 Resources

• Website
• Pricing
• Discord
• Slack
• X
• Changelog
• Examples
• Security policy

📃 License

The SDK is open source under the MIT license; see LICENSE. Parts are derived from other MIT-licensed SDKs; see NOTICE.

😘 Contributors

Thanks to everyone who helps make Fixwire better!