# Custom WordPress Plugin Development

> Custom WordPress plugin development: Gutenberg blocks, custom post types, REST API, member areas and connectors, on a fixed quote with the source code handed over.

- Page: <https://www.datafirefly.com/en/expertise/wordpress-plugin-developer/>
- Language: en
- Last updated: 2026-09-24
- Other languages: [fr](https://www.datafirefly.com/expertise/developpeur-plugin-wordpress/index.md), [es](https://www.datafirefly.com/es/pericia/desarrollador-plugins-wordpress/index.md), [de](https://www.datafirefly.com/de/fachkompetenz/wordpress-plugin-entwickler/index.md), [it](https://www.datafirefly.com/it/competenze/sviluppatore-plugin-wordpress/index.md), [pl](https://www.datafirefly.com/pl/ekspertyza/programista-wtyczek-wordpress/index.md), [nl](https://www.datafirefly.com/nl/expertise/wordpress-plugin-ontwikkelaar/index.md), [pt](https://www.datafirefly.com/pt/expertise/programador-plugins-wordpress/index.md)
- Index: <https://www.datafirefly.com/en/expertise/llms.txt>

A WordPress plugin is quick to write and just as quick to break: a hook fired at the wrong moment, an unsanitised option, an unprepared query, and the whole site goes down at the next update. We build custom WordPress plugins that survive updates to WordPress, PHP and your other extensions, with a written scope and a fixed price agreed before we start.

The site you are reading is an example: datafirefly.com runs on a theme and plugins written in-house, including an MCP server that publishes and translates content in eight languages. We know WordPress as a production tool, not just as a blog engine.

Is your project about a WooCommerce store? See our [custom WooCommerce extension](https://www.datafirefly.com/en/expertise/woocommerce-extension-developer/) page instead, which covers checkout, HPOS and payment gateways in detail.

## What we build on WordPress

### Content types and admin screens

Custom post types, taxonomies, structured fields, dedicated admin screens, columns and filters in list tables. The goal: your team enters clean content without relying on a page builder.

### Gutenberg blocks

Static or dynamic blocks, variations, patterns and sidebar settings. A server-rendered dynamic block keeps control of the HTML and avoids frozen content when the design changes.

### REST API and integrations

Secured REST endpoints, incoming and outgoing webhooks, sync with a CRM, an email platform or a business application. Heavy processing runs in scheduled tasks so page rendering is never blocked.

### Member areas and restricted content

Registration, access levels, paid content, user dashboards. WordPress roles and capabilities are used as they are, with no parallel permission system.

### Multilingual sites

Plugins built for Polylang and WPML from the start: translatable strings, content linked across languages, localised URLs. It is the setup of our own site, in eight languages.

## How we write a WordPress plugin

- **Security by default**: nonces on every action, capability checks, input sanitised and output escaped, queries prepared with `$wpdb->prepare()`.
- **Performance**: no queries inside loops, options loaded on demand, transient caching for external calls, assets loaded only on the pages that need them.
- **Clean activation and uninstall**: tables created by versioned scripts, data removed on uninstall if you ask for it.
- **Extensible**: documented actions and filters so another developer can adapt the plugin without editing its code.
- **Compatible with current versions** of WordPress and PHP, tested with your theme and plugins on a staging copy.

## What you receive at delivery

- The plugin as a ZIP installable from the WordPress admin.
- The complete source code with no restrictive licence.
- User documentation and the list of exposed hooks.
- 12 months of compatibility updates and bug fixes.

## What drives the price of a WordPress plugin

Our quotes start at €1,200 and stay fixed once the scope is approved.

| Factor | Effect on the quote |
| --- | --- |
| Interface | A few settings on an options page, or a full admin area with lists, filters and exports. |
| Gutenberg blocks | A static block is quick; a dynamic block with editor preview and advanced settings takes longer. |
| External integration | A documented, stable API, or a tool that forces file imports and more careful error handling. |
| Multilingual | A single-language site, or content linked across several languages with Polylang or WPML. |

## Around the plugin

We also work as [WordPress developers](https://www.datafirefly.com/en/expertise/wordpress-developer/) on existing sites, and publish a catalogue of documented WordPress and WooCommerce plugins that we can adapt to your needs.