Expression workspace
Choose a recipe, edit it, and run locally with your own sample JSON context.
Expression editor
Power Automate-style syntaxEvaluation & test data
Everything is processed in this browserYour evaluation will appear here.
This lab simulates a documented subset of expressions. It is not Microsoft's runtime, and some conversions and runtime behaviour may differ.
Edit trigger.body, actions, variables, parameters, items or the sample “now” value. This JSON stays in your browser.
Explore supported functions
Browse the local evaluator’s supported subset. Select any function to load an editable example in the lab.
· These are implemented in the local evaluator; not the full Power Automate function library. Official Microsoft reference ↗
Take the lab with you
No installation, accounts or backend. Use the same lab when you are offline or working in a restricted environment.
Open a single HTML file
Double-click the downloaded HTML. All evaluation logic and styles are bundled inside.
Zero remote evaluation
Enter expressions and sensitive sample data locally. Avoid copying real secrets into any tool.
Inspect the code
MIT-licensed source, tests, and CI definitions are included for independent review.
Network transparency
Check exactly what the page loads. Your expressions, context and results are not transmitted by this application.
Resource request summary
| Domain | Visible requests |
|---|---|
| No resource timing data available yet. | |
How to verify independently
On a desktop browser, press F12, choose Developer Tools → Network, enable Preserve log, then reload and inspect network activity.
Online edition requests the Mightora shared CSS/JS, footer configuration, js-yaml and images. The offline edition loads no external assets.
Resource Timing may omit blocked, cached, cross-origin or very early requests. The on-screen summary is not a security audit or a replacement for Developer Tools.
Guidance & frequently asked questions
Practical tips to move from a test expression into a real flow.
Can I paste a Power Automate expression directly?
Yes. Expressions may start with @, or be written without it as in the expression designer. You can also test text interpolation using @{...}. Some supported syntax such as nested functions and null-safe bracket access works with supplied JSON context.
How do I mock trigger and action data?
Choose “Mock context”, edit the JSON, and use triggerBody()?['field'], body('Action_name')?['field'], variables('name') or outputs('Action_name')?['property']. Action keys should match the names in your expression.
Does this run a Microsoft Power Automate flow?
No. This is an independent offline simulator for a documented subset, not a Microsoft product or authoritative WDL engine. It cannot call connectors, access your tenant, or reproduce all runtime coercion and date/time functionality. Always test your final expression in a real flow.
Are expressions uploaded, stored or sent to a service?
No. The application does not submit expressions or context to a server, and does not save them between sessions. The online page fetches shared brand components and imagery; the offline HTML makes no application network requests.
What if my function is not listed?
Use Microsoft's official function reference and validate in Power Automate. The evaluator will tell you a function is not supported instead of guessing at its result.
