PluginScout

Duplicate Killer

Duplicate Killer – Prevent Duplicate Form Submissions

by NIA · WordPress.org page

v1.6.9 Tested up to WP 7.0.4 PHP 5.6.20+ Paid version available

Duplicate Killer has 1,000+ active installs on WordPress.org and 28,797 downloads all time. We have tracked it since September 4, 2026; download trends appear after 30 days of data. The last update was on August 4, 2026, tested up to WordPress 7.0.4.

Duplicate Killer at a glance

Active installs
1,000+
Total downloads
28,797
Downloads, last 30 days
–
available after 30 days of tracking
30-day growth
–
tracking since September 4, 2026

Is Duplicate Killer well maintained?

Support threads resolved
No open threads
nothing waiting on the WordPress.org forum
WordPress compatibility
Behind
tested up to WordPress 7.0.4, not yet with the current 7.1

Features

The feature list from the plugin's own readme on WordPress.org, trimmed to the essentials.

  • Protect multiple forms
  • Per-form duplicate protection rules
  • Cross-Form Duplicate Protection (detect duplicates across different forms)
  • Custom error message for each form
  • Different IP limits per form
  • Unique entries per user, configurable per form
  • Designed for sites with multiple forms and different submission needs
  • Duplicate Killer PRO is ideal for sites with multiple forms and different audiences

Duplicate Killer reviews and ratings

3 reviews on WordPress.org, with the most recent ones as their authors posted them.

All reviews
5.0 out of 5

3 reviews

5★
3
4★
0
3★
0
2★
0
1★
0

  • Great and straightforward plugin

    Plugin is straightforward and the support is really responsive and helpful.

    jeng22

  • Fixed the issue with duplicate CF7 Emails!!

    There seems to be an issue with CF7 where duplicate emails are sent out, and the forms render errors/loading spinners twice as well. I've done a good bit of research and looked everywhere, but had no luck finding a fix for this. This plugin resolved the issue straight away with no configuration needed! Thank you!

    hambad

  • Works like a charm

    This solves my duplicate entries headache - works as intended. Thanks!

    peterlovescola

Duplicate Killer alternatives

Plugins that solve the same problem, ranked by how closely they overlap with Duplicate Killer.

All Duplicate Killer alternatives

Details

Block duplicate form submissions by validating unique email, phone and text fields without CAPTCHA.

The full description, screenshots and every review live on the WordPress.org page.

Tags

  • contact form 7
  • duplicate submissions
  • duplicate-orders
  • elementor forms
  • woocommerce

More from NIA

Version
1.6.9
Last updated
Aug 4, 2026
First published
Oct 7, 2022
Requires WordPress
5.3
Tested up to
7.0.4
Requires PHP
5.6.20
Pricing
Free, paid version available

Duplicate Killer FAQ

What does Duplicate Killer do?

According to its WordPress.org readme, Duplicate Killer offers Protect multiple forms, Per-form duplicate protection rules, Cross-Form Duplicate Protection (detect duplicates across different forms), Custom error message for each form and Different IP limits per form.

How many active installs does Duplicate Killer have?

WordPress.org reports 1,000+ active installs for Duplicate Killer as of September 7, 2026.

Is Duplicate Killer still maintained?

Yes. The last release was on August 4, 2026 and it is tested up to WordPress 7.0.4.

Is Duplicate Killer free?

Duplicate Killer is free to install from WordPress.org. The developer lists it as commercial, so a paid version or paid add-ons exist.