Two New API Services for Power Platform Makers: URL Validator & Bi-directional Markdown ↔ HTML Converter

A community spotlight on two open-source utilities by Hüseyin KORHAN

If you've ever built a Power App or Power Automate flow that accepts user-submitted links, processes content from SharePoint, or sends formatted emails through Outlook, you've probably run into two frustratingly common problems:

1. How do I reliably check that a URL is valid — and actually reachable — without writing convoluted regex inside a Power Fx formula?
2. How do I convert Markdown to HTML (or HTML back to Markdown) inside a flow without paying for a premium third-party connector?

Power Platform community contributor Hüseyin Korhan (GitHub · LinkedIn · zetaleap.com) has just released two open-source API services that tackle exactly these scenarios. Both are designed with low-code makers in mind and plug cleanly into Power Automate via the HTTP action or a custom connector.

Let's take a look at each one.

1. URL-Validator-API

🔗 Repository: github.com/korhanh/URL-Validator-API

The problem it solves

Inside Power Apps and Power Automate, URL validation has traditionally meant copy-pasting long regular expressions into IsMatch() formulas. The community has been working around this for years — there are entire blog posts dedicated to crafting the "right" regex for the job, with users debating whether expressions like (?:http(s)?:\/\/)?[\w.-]+(?:\.[\w\.-]+)+... actually handle subfolders, query strings, and encoded characters properly.

Even when the regex works, it only tells you whether the format looks like a URL. It can't tell you whether the link actually points to a live page — something that matters a lot when your flow is about to email a customer a broken link or write a dead URL into a Dataverse table.

What it does

The URL-Validator-API is a lightweight REST endpoint you can call from any Power Platform asset. Conceptually it follows the same pattern popular in the JavaScript ecosystem, where validator libraries typically offer two complementary checks: ensuring the URL follows correct syntax, and verifying that it's reachable via an HTTP request. Good validators also confirm proper protocols (only http:// and https://), validate the domain and top-level domain, and block invalid IP addresses.

By exposing those checks as a single API call, the service lets you:

• Validate format (protocol, domain, TLD, no spaces, no malformed IPs)
• Check liveness by issuing an HTTP request and inspecting the status code
• Handle redirects gracefully so a 301 or 302 is still considered valid
• Return a clean JSON response that's trivial to parse with parseJSON() in Power Automate

Why Power Platform makers will love it

• No regex in your canvas app. Replace 200-character IsMatch() formulas with a single HTTP call (or, even better, a custom connector action named "Validate URL").
• Cleaner data in Dataverse and SharePoint. Catch dead links before they're stored.
• Better email automation. Validate every hyperlink before a Power Automate flow blasts a newsletter or notification.
• AI-builder friendly. When using GPT-generated content that includes citations, you can validate every link the model produced before publishing.

Sample Power Automate usage

POST https://your-deployment/api/validate
Content-Type: application/json

{
  "url": "https://learn.microsoft.com/power-platform/",
  "checkLive": true
}        

Expected response:

{
  "isValid": true,
  "isLive": true,
  "statusCode": 200,
  "redirects": 0
}        

You can then use a simple Condition step on body('Validate_URL')?['isValid'] to branch your flow.

2. Bi-directional-Markdown-HTML-Converter-API

🔗 Repository: github.com/korhanh/Bi-directional-Markdown-HTML-Converter-API

The problem it solves

Markdown ↔ HTML conversion is one of the most-requested missing features in Power Automate. There are open community ideas for both Convert HTML to Markdown and Create a markdown to html converter action on the official Power Automate Ideas portal — proof that makers genuinely need this every day.

Today's workarounds aren't great:

• Cloudmersive provides a "Convert Markdown to HTML" action in Power Automate, but using it requires a premium Power Automate license (because it's a third-party connector), and the free-tier API key is limited to 800 API calls per month.
• Rolling your own conversion logic inside a flow using nested replace() expressions is brittle and unmaintainable.
• Cloud actor-style alternatives exist (such as Apify's Markdown ↔ HTML Converter), but they're built for general developer pipelines, not specifically for low-code makers.

What it does

This API does exactly what the name says — converts in both directions, in a single endpoint:

• Markdown → HTML, so you can take user-friendly content (from a Power Apps multi-line text input, an AI Builder prompt response, or a Copilot Studio answer) and inject it into an Outlook email body, a SharePoint page, or a Power Pages article.
• HTML → Markdown, so you can ingest formatted email bodies, scraped pages, or rich-text Dataverse columns and pipe them into LLMs, Git repositories, or any system that prefers Markdown.

Most modern bi-directional converters of this kind support GitHub Flavored Markdown (GFM) by default — including tables, strikethrough, and task lists — and the industry standard under the hood is usually the marked library for Markdown→HTML and turndown for HTML→Markdown. Both libraries are production-tested and widely trusted. If Hüseyin's API follows that same convention (which is the sensible choice), you get reliable, predictable output without re-inventing parser logic.

Why this matters for Power Platform makers

Pair this with Hüseyin's earlier project — a detailed guide on creating HTML tables in Outlook emails using Microsoft Power Automate, where you can easily extract data, convert it into an HTML table, and style it with CSS (Power-Automate-HTML-Table-Formatting) — and you have an end-to-end story for content automation:

1. Author content in Markdown (it's easier to write, store, and version-control).
2. Convert to HTML on the fly inside a flow.
3. Combine with formatted HTML tables.
4. Send via Outlook, post to Teams, or push to SharePoint.

Some concrete scenarios:

ScenarioDirectionOutlook email body from a Markdown template in SharePointMD → HTMLSave a scraped article into a Dataverse "knowledge base" tableHTML → MDFeed cleaner content to Azure OpenAI / Copilot Studio for summarisationHTML → MDRender Markdown stored in a Power App's text variable as styled HTMLMD → HTMLMigrate a legacy HTML wiki to a Markdown-based docs systemHTML → MD

Sample request

POST https://your-deployment/api/convert
Content-Type: application/json

{
  "input": "# Release notes\n\n- New feature\n- **Bug fix**",
  "direction": "mdToHtml"
}        

Response:

{
  "output": "<h1>Release notes</h1>\n<ul>\n<li>New feature</li>\n<li><strong>Bug fix</strong></li>\n</ul>"
}        

Swap "mdToHtml" for "htmlToMd" and the API runs the opposite direction.

Why I think both are worth publishing

A few reasons these two services stand out from the dozens of generic validators and converters already floating around on GitHub:

1. They're API-first, not library-first. That makes them immediately consumable from Power Automate's HTTP action, Power Apps custom connectors, Copilot Studio plugins, Logic Apps, and even Excel Office Scripts — without any code on the maker's side.
2. They directly fill documented gaps in the Power Platform community ideas portal (see the linked HTML-to-Markdown and Markdown-to-HTML community ideas above).
3. They're maintained by a maker who already builds for the Power Platform. Hüseyin's existing repo on HTML table formatting in Outlook shows he understands the ecosystem's real pain points — not generic dev problems.
4. They're free and open-source, which means they sidestep the premium-connector tax that's pushed many makers away from third-party converters like Cloudmersive.

Recommendations before going to production

If you're planning to roll either service into a corporate Power Platform tenant, I'd suggest:

• Host it inside your own Azure subscription (Azure Container Apps, App Service, or Functions). That puts you in control of latency, data residency, and DLP boundaries.
• Wrap both APIs in a single custom connector with two operations — ValidateUrl and ConvertMarkup. Makers will love the autocomplete UX inside the flow designer.
• Add an API key or Entra ID auth before exposing it widely. Validation and conversion endpoints are easy targets for abuse if left open.
• Cache HTML→Markdown conversions for frequently-seen URLs. The HTTP fetch (in the validator) plus parsing (in the converter) is where almost all the cost lives.

Final verdict

Yes — both projects are absolutely worth a feature. They fill genuine, well-documented gaps for Power Platform makers, the author has a track record of building practical Power Automate tooling, and they're packaged in exactly the right shape (REST APIs returning clean JSON) for low-code consumption.

I'd encourage anyone reading this to:

• ⭐ Star the repositories on GitHub:URL-Validator-APIBi-directional-Markdown-HTML-Converter-API
• 👀 Browse Hüseyin's other Power Platform work at github.com/korhanh
• 🤝 Connect with him on LinkedIn
• 🌐 Visit his website at zetaleap.com

Hüseyin — thanks for sharing these with the community. Looking forward to seeing what you ship next. 🚀