Practical Opt-In Telemetry for Indie Developer Tools

Developer tools that ship with silent telemetry lose trust quickly. Developers read the source, inspect network calls, and talk to each other. At the same time, a solo maintainer flying completely blind makes worse prioritization decisions: which command is actually used, which flag is broken in the wild, whether a new major version is adopted.

This is a practical operating guide for indie CLI, SDK, and library authors. The goal is a small amount of useful signal that is off by default, clearly disclosed, and easy for users to turn off permanently. It is not a blueprint for a full product-analytics stack.

Decide whether you need telemetry at all

Many small tools never need it. If you have a single command, a handful of users who email you, and a public issue tracker that already surfaces problems, skip telemetry. The overhead of consent, documentation, and data handling is higher than the value.

Telemetry becomes useful when:

• You have multiple subcommands or entry points and cannot tell which ones are dead.
• Users report “it crashes” without a reproducible case, and a minimal crash report would help.
• You are about to deprecate a flag or API surface and want evidence that almost no one still uses it.
• You ship binary releases and want a rough sense of which OS/architecture combinations are in active use.

If none of those apply, do not add it. Adding telemetry “just in case” creates ongoing privacy and support obligations for little gain.

What is reasonable to collect (and what is not)

Keep the payload small and non-identifying. Illustrative fields that are usually acceptable when the user has opted in:

• Tool version and the specific command or function that ran.
• Success or failure (exit code or a coarse error category, not the full stack or user input).
• OS, architecture, and runtime version (Node, Python, Go, etc.).
• A coarse duration bucket (under 100 ms, under 1 s, longer) rather than exact timings that could fingerprint.
• An anonymized install or session identifier that resets if the user opts out, or no persistent identifier at all.

Never send, even with consent:

• File paths, arguments, environment variables, or stdin content.
• Hostnames, usernames, IP addresses, or precise geolocation.
• Source code, configuration values, or secrets.
• Full stack traces that may contain user data; redact or omit them.
• Any data that would let you map activity back to a specific person or company without additional effort.

If you cannot articulate why a field is useful for prioritization or debugging, leave it out. The smaller the payload, the easier it is to defend and the less likely it is to surprise someone who inspects the traffic.

Default off, explicit opt-in, easy opt-out

The default must be off. On first run (or first interactive use), show a short, non-blocking notice:

This tool can send anonymous usage data (command name, version, success/failure, OS). No file paths, arguments, or personal data. Enable it? [y/N]

Accept only an explicit yes. Store the choice in a local config file (for example ~/.config/mytool/telemetry.json or an equivalent XDG path) with a clear key such as enabled: true/false. On subsequent runs, respect that file without asking again.

Also support:

• A flag (--no-telemetry or --telemetry=false) that overrides for a single invocation.
• An environment variable (MYTOOL_TELEMETRY=0) that forces off for CI and scripts.
• A command (mytool telemetry off) that writes the disabled state and deletes any local identifier.

Document the exact fields and the opt-out methods in the README and in a short TELEMETRY.md or docs page. Link to it from the first-run prompt. Users who care will look; users who do not will still have a working tool.

Implementation patterns that stay small

You do not need a custom backend on day one.

• CLI (Go, Rust, Node, Python): After the command finishes, if telemetry is enabled, POST a small JSON body to a simple endpoint (a serverless function, a Cloudflare Worker, or even a form endpoint that writes to a spreadsheet or database). Fire-and-forget with a short timeout (1–2 seconds). Never block the user’s command on the network call. Catch and ignore all errors so telemetry cannot break the tool.
• SDK or library: Prefer not to phone home from library code. If you must, gate it behind an explicit init({ telemetry: true }) call and document it. Many library users will reject any network activity by default.
• Crash reporting: A separate, even more explicit opt-in for crash reports is reasonable. Include a prompt that shows the exact payload (or a redacted version) before sending, or let the user copy a local crash file and paste it into an issue. This is often more useful and less controversial than continuous telemetry.

Store the opt-in decision only on the user’s machine. Do not create an account or require a login just to enable telemetry.

How to use the data without over-interpreting it

Opt-in telemetry is biased. The people who enable it are not a random sample; they are often more technical, more engaged, or more privacy-conscious in the opposite direction. Treat the numbers as directional signals, not ground truth.

Useful questions the data can answer:

• Which commands or API methods appear in more than a handful of sessions?
• Are users still on an old major version months after you shipped a new one?
• Does a particular OS/architecture combination show a higher failure rate?
• Did a recent release increase the proportion of failed runs?

Do not use the data to claim “X% of users do Y” in marketing. The sample is self-selected. Use it internally to decide what to keep, what to deprecate, and where to look for bugs.

If volume stays tiny (a few dozen events per week), a simple dashboard or even a weekly SQL query or spreadsheet is enough. You do not need real-time charts.

Practical checklist before you ship it

• Default is off; first-run prompt requires an explicit yes.
• Opt-out is possible via flag, environment variable, and a persistent config command.
• Payload is documented and contains no paths, arguments, user content, or identifiers that can be tied to a person.
• Network call is non-blocking, times out quickly, and never fails the user’s command.
• README and docs explain what is collected and how to disable it.
• CI and script usage is forced off by default or by an obvious environment variable.
• You have a way to delete or stop receiving data if a user later opts out (or you simply do not retain long-term identifiers).
• The receiving endpoint is cheap to run and does not store raw request logs that re-identify users.

Common pitfalls

• Shipping with telemetry on by default “just for the first few weeks.” Users who discover it later will not trust future releases.
• Including the full command line or a config snippet “to make debugging easier.” That is the fastest way to lose trust.
• Making the opt-out hard to find or requiring a reinstall. Persistent local config plus an environment variable is the minimum.
• Blocking the main command while waiting for the telemetry request. Latency or a downed endpoint should never affect the user.
• Treating early opt-in numbers as representative and building a roadmap around them. Cross-check with GitHub issues, support email, and direct conversations.

When the simple approach is no longer enough

Revisit or remove telemetry when:

• You start selling to companies that require a Data Processing Agreement or forbid any outbound calls.
• The volume of events justifies a proper pipeline and you want better sampling or retention controls.
• Users repeatedly ask for a fully air-gapped or offline mode that you cannot currently guarantee.
• You realize you are not looking at the data and the collection is pure overhead.

Until then, default-off, a tiny payload, clear documentation, and a non-blocking send will give most solo maintainers the signal they need without creating a support or trust problem. If the data never changes a decision, turn it off. The tool should work perfectly for people who never enable it.

Telemetry is optional infrastructure, not a feature. Treat it that way and most users will either ignore it or appreciate that you asked first.