Flag Rules · Free Local Tool

Feature Flag Rule Simulator

Simulate Feature Flag hit results and determine trajectories based on user Context, condition priority, and percentage offloading.

No uploadsMobile-friendlyTheme support

Feature Flag What is the Rules Simulator?

Simulate Feature Flag hit results and determine trajectories based on user context, condition priority, and percentage shunting. ToolHub places the core computing entirely within the browser, allowing immediate use on both desktop and mobile devices, without the need to register an account or send content to the backend.

How to use this tool?

  1. Enter the data according to the field prompts and select the required processing method.
  2. Click "Process Now" to view the results, indicator summary and necessary error messages.
  3. After confirming that the content meets actual needs, you can copy the results or download them into files for further use.

Suitable use cases

Grayscale publishing, A/B testing, permission diversion and setting QA. All processing is completed in the current page, which is especially suitable for workflows that do not want to post internal data to remote services.

Interpretation of results and precautions

Hash and conditional syntax are the model of this tool and need to be compared with the actual Feature Flag platform before importing. Tools will validate basic input formats and provide readable error messages, but production environments should still be reconfirmed against source specifications, business rules, or professional requirements.

Browser and device support

Feature Flag Rule Simulator supports current Chrome, Edge, Firefox, and Safari releases. Mobile and desktop layouts use the same validation rules documented on this page.

Frequently Asked Questions

Feature Flag Will the rules simulator upload data to the server?
No. Tool functions are executed directly within the current browser tab, and input and generated results will not be uploaded or saved by ToolHub.
What usage scenarios is Feature Flag Rules Simulator suitable for?
Grayscale publishing, A/B testing, permission diversion and setting QA
Do I need to install software before using the Feature Flag rule simulator?
No need. Use a desktop or mobile browser that supports modern JavaScript, and no account is required.
What are the limitations of this tool?
Hash and conditional syntax are the model of this tool and need to be compared with the actual Feature Flag platform before importing.
Is manual inspection required after the results are generated?
Needed. Tools can assist with calculations, conversions, or formatting, but before going online, importing data, or making business decisions, the results should still be reviewed according to actual specifications.

Feature Flag Rule Simulator: inputs, output, and reproducible example

Use the free Feature Flag Rule Simulator online. Fast, private, mobile-friendly, and processed directly in your browser.

What this page actually processes

FieldControlDefault exampleValidation role
Flag KeyTextnew-dashboardFlag Key is read by the browser as a text value before the tool runs.
User Context JSONMultiline text{"userId":"user-1042","country":"TW","tier":"pro","age":28}User Context JSON is read by the browser as a multiline text value before the tool runs.
Rule JSONMultiline text[{"name":"Taiwan Pro","conditions":[{"field":"country","op":"eq","value":"TW"},{"field":"tier","op":"eq","value":"pro"}],"variant":"enabled"Rule JSON is read by the browser as a multiline text value before the tool runs.
Default VariantTextcontrolDefault Variant is read by the browser as a text value before the tool runs.

Reproduce the built-in example

Start with Flag Key = new-dashboard; User Context JSON = {"userId":"user-1042","country":"TW","tier":"pro","age":28}; Rule JSON = [{"name":"Taiwan Pro","conditions":[{"field":"country","op":"eq","value":"TW"},{"field":"tier","op":"eq","value":"pro"}],"variant":"enabled"; Default Variant = control, then run Feature Flag Rule Simulator. Change one input at a time so the effect on the result remains traceable.

After validating flag key, user context json, rule json, default variant, the page displays its result in the output workspace and enables the relevant copy or download action.

When to use it and how to interpret the result

Grayscale publishing, A/B testing, permission diversion and setting QA. All processing is completed in the current page, which is especially suitable for workflows that do not want to post internal data to remote services.

Limits and checks before use

Hash and conditional syntax are the model of this tool and need to be compared with the actual Feature Flag platform before importing. Tools will validate basic input formats and provide readable error messages, but production environments should still be reconfirmed against source specifications, business rules, or professional requirements.

Page verification record

Controls inspected4 documented inputsResult pathValidate → process → review → copy/downloadLast content review2026-09-02