Custom WordPress plugin development
The plugin you need, written to survive every update.
One focused plugin instead of five that half-fit. We spec it, build it on WordPress’s own APIs, review it for security line by line and hand you the full source code.
Security reviewed
Translation ready
Tests + docs
- OK
your-plugin.phpUnique prefix, direct-access guard in place - FOUND
admin/settings.php:88Form saved without a nonce check - FOUND
includes/api.php:41REST route missing permission_callback - WARN
templates/list.php:12Output not escaped — esc_html() added - OK
includes/db.phpEvery query uses $wpdb->prepare() - OK
languages/All strings ready for translation - OK
reviewIssues fixed — ready for staging
2 issues found · 2 fixed
Why the code matters
Almost every WordPress vulnerability lives in a plugin.
Patchstack’s 2026 report counted only six vulnerabilities in WordPress core during 2025. The rest were in the plugins and themes built on top of it — which is why how a plugin is written matters as much as what it does.
91%
of new WordPress ecosystem vulnerabilities in 2025 were in plugins
11,334
new vulnerabilities disclosed in 2025 — 42% more than the year before
29%
were in premium or freemium components — paying for a plugin is no guarantee
Build or buy?
Do you actually need a custom plugin for WordPress?
Often the honest answer is no — a well-maintained plugin from the directory will do. Tick what sounds like your site and we’ll tell you which way it leans.
Do the maths
What your current setup already costs.
Licence renewals and manual work add up quietly. Enter your own numbers and compare the total with the written quote for one plugin you own outright.
Only your inputs are used — no industry averages. Hosting and ongoing maintenance are left out on both sides.
Your current setup, over the years you chose
$17,271Spent over the period on licences and manual work
- Per year
- $5,757
- Staff hours per year
- 156h
Compare this with your fixed written quote. A custom plugin has no renewal fee, but budget for keeping it up to date.
Secure by design
Where plugin vulnerabilities come from — and how we close each one.
Most flaws in Patchstack’s database fall into a handful of types, and WordPress ships an API for each of them. Select a segment to see the mistake and the defence we write into every plugin.
Cross-site scripting (XSS) 31.3%
Untrusted data printed straight into a page. We escape as late as possible with esc_html(), esc_attr(), esc_url() and wp_kses(), right where data is output.
Broken access control 20.3%
An action anyone can trigger that only admins should. Every action checks current_user_can(), and every REST route has a real permission_callback.
SQL injection 7.9%
User input glued into a database query. Every custom query goes through $wpdb->prepare() with typed placeholders.
Sensitive data exposure 4.8%
Keys, emails or order data leaking through public endpoints, logs or files. We expose only what a screen needs and keep secrets out of the browser.
Cross-site request forgery (CSRF) 4.1%
A logged-in user tricked into submitting a form. Every form and AJAX action carries a nonce — on top of capability checks, never instead of them.
Arbitrary file upload 2.1%
Uploads that let an attacker drop a PHP file on the server. We validate file types and route uploads through WordPress’s own handlers.
Other types 29.5%
Everything else, from privilege escalation to file inclusion. The same rule applies: never trust input — validate, sanitise, escape and check permissions.
Source: Patchstack database — WordPress vulnerability statistics
Update-safe by design
Hooks, not hacks — so updates can’t undo it.
The Plugin Handbook’s first rule is “Don’t touch WordPress core”, because updates overwrite it. We extend WordPress only through its hooks and public APIs, so core, theme and plugin updates keep flowing.
- Stable, documented APIsActions, filters, the REST API and the settings API — not copies of core functions or edited third-party files.
- No naming collisionsEvery function, class and option carries a unique prefix, as the handbook recommends.
- Loads only where it’s neededAdmin code stays in the admin and scripts load on the pages that use them, so the rest of the site stays light.
The rulebook we follow
Written to WordPress’s own standards.
No house style to decode later. A WordPress plugin developer who has never seen your code should be able to pick it up and carry on.
Coding standards
Code that reads like one person wrote it
WordPress’s coding standards exist to “avoid common coding errors, improve the readability of code, and simplify modification” — for PHP, JavaScript, CSS and HTML.
Security handbook
Never trust input. Escape late.
Validate and sanitise everything that comes in, escape everything that goes out, check capabilities on every action and add nonces to every form.
Plugin Check
The directory’s own test suite
We run WordPress.org’s Plugin Check before handover — the same checks used for new directory submissions, covering security, performance, accessibility and translation.
WordPress API integration
Your website and your systems, finally in sync.
Forms that land in your CRM, orders that reach your ERP, members that sync with your email tool — without anyone copying and pasting.
- CRMs, ERPs, payments and emailOr your own internal API — one-way pushes or two-way syncs.
- Built to fail gracefullyBackground jobs, retries and logs, so a slow third-party API never blocks a visitor.
- Endpoints locked downCustom REST routes always declare a permission check — WordPress has flagged routes without one since version 5.5.
From idea to installed plugin
A spec first. Then code you can test early.
You see the plan before we write a line, and for larger plugins you test a working prototype in the first weeks.
-
Agree exactly what it does
A short written spec: what the plugin does, who uses it and how it connects to your other systems.
- User roles and permissions
- Data it stores and where
- Integrations and edge cases
-
Try the core feature early
For larger plugins we build a working prototype of the main feature, so you can test it before the rest is built.
- Core feature on staging
- Your feedback round
- Spec adjusted if needed
-
Finish it properly
We complete the plugin, add automated tests for the key features and run it on a staging copy of your site.
- Security review and Plugin Check
- Tests on a recent WordPress and PHP
- Readme and inline docs
-
Live, watched and supported
We install it on your live site, monitor it and fix any bugs during the support window.
- Live install and smoke test
- Monitoring after launch
- Full source code handed over
Ballpark it
What a custom plugin usually involves.
Pick what sounds closest to your idea for a rough range. After we read your requirements, you get one fixed price in writing.
Handover
Yours to keep, easy to hand on.
You get the full source code to host in your own repository, with everything the next developer needs to understand it.
- Readme and inline commentsWhat it does, how to configure it and why the tricky parts work the way they do.
- Automated testsTests for the key features, so future changes can be checked in minutes.
- Translation readyEvery string wrapped for translation, so it works on multilingual sites.
Questions, answered
How do you check a plugin is secure?
We follow WordPress’s security handbook throughout — validate and sanitise input, escape output, check capabilities, add nonces and prepare every query — then review the code by hand and run WordPress.org’s Plugin Check before handover.
Aren’t nonces enough to protect a form?
No. WordPress’s own documentation says nonces “should never be relied on for authentication, authorization, or access control”. They stop forged requests; capability checks decide who is allowed to act. We use both.
Who owns the plugin?
You do. We hand over the full source code, and you can host it in your own repository.
Can you fix or extend a plugin someone else wrote?
Yes. We review the code first and tell you whether extending it or rewriting it makes more sense.
Can you publish the plugin on WordPress.org?
Yes. We can prepare it to meet the plugin directory guidelines and handle the submission with you.
Do you build WooCommerce extensions?
Yes. For store-specific features, see our WooCommerce development service.
What if a WordPress update breaks it?
We write plugins against stable APIs to avoid that. If something does break during the support window, we fix it at no charge.
Get a free quote
Let’s build something great.
Tell us about your project and goals. A WordPress engineer — not a salesperson — will reply within one business day with a plan and a fixed price.
- Free, no-obligation quote within 24 hours
- NDA available on request
- Fixed price — you approve the scope before work starts
