modsignal vs changedetection.io
A changedetection.io alternative for teams who don't want to run one.
changedetection.io is excellent open source — if you want to self-host, use it. modsignal is for the other case: no Docker, no selector upkeep, and a model that reads the page instead of diffing its text.
Try modsignal freeThe DPA now allows subprocessor changes with 14 days' notice, down from 30.
Let's be straight: changedetection.io is very good. Thirty-thousand-plus GitHub stars, an active maintainer, and if you're comfortable running Docker containers and tuning visual selectors, self-hosting it costs you nothing but your time. Plenty of people should just use it, and we're not going to pretend otherwise.
modsignal is for the case where that time isn't free. Someone has to keep the container updated, wire the proxies when sites object, maintain the selectors and trigger keywords when pages re-render, and explain to the rest of the team what the diff means. And underneath all that, the detection is still textual: changedetection.io can tell you the words changed, but not whether the change you actually care about happened. "Filter to this div, trigger on these keywords" is the ceiling.
modsignal's semantic tier raises that ceiling: you describe the change in plain language, a model reads each new version of the page against your description, and you get one sentence with the before, the after, and a confidence score when — and only when — it happened. There's a hosted changedetection.io at $8.99/month if all you want is managed diffing; modsignal's free tier covers three monitors with the semantic tier included, so you can compare what judgment adds before paying anything.
changedetection.io vs modsignal, side by side
Competitor details verified against public pricing pages and reviews in July 2026 — check their site for current numbers.
| changedetection.io | modsignal | |
|---|---|---|
| Hosting | Self-hosted via Docker (free), or hosted service at $8.99/mo | Fully hosted on every plan, including free |
| Setup and upkeep | Container updates, proxy configuration for protected sites, visual selectors, trigger keywords | Paste a URL, write a prompt. Nothing to maintain |
| Detection model | Text/visual diff with filters and keyword triggers — no semantic layer | Exact diff when you want every change; semantic AI when only some changes matter; browser agent for JS-heavy pages |
| What an alert looks like | Diff notification via Apprise (80+ services) | One sentence stating what changed, with before/after evidence and a confidence score |
| Teams | Single-instance tool; sharing means sharing the instance | Teammates, shared monitors, and shared alert history on every plan |
| Cost | Free (your infrastructure and time), or $8.99/mo hosted | Free: 3 monitors, daily. Pro $25/mo: 25 monitors, every 15 min, 5 teammates |
Choose changedetection.io if
- You want self-hosted and open source on principle, or your pages can't leave your network.
- You enjoy running your own infrastructure and the maintenance time is genuinely free to you.
- You need its long tail of power features — browser steps for logins, 80+ notification backends via Apprise.
Choose modsignal if
- You're setting this up for a team, and "ask the person who runs the container" isn't an alert workflow.
- You need to know whether the change matters, not just that text moved — a diff can't tell you a subprocessor left the EU.
- You want evidence-backed alerts a non-technical teammate can read and act on directly.
Set up the monitor that stays quiet.
Write the prompt, set the interval and get the first alert when something actually changes. Free plan, no credit card.