Dev tools · alternatives · 2026

24 alternatives to Diffly

Catch API changes before they break your app.

Below are 24 products that do a similar job, ranked by how close each is in meaning and then by launch-day votes.

1
API Diff▲161
Diff two API versions in seconds and see what has changed
2022 · api-diff.io · its alternatives →
2
What The Diff▲188
Your AI-powered code review assistant
2022 · whatthediff.ai · its alternatives →
3
API Changelog▲191
APIs change. Don't get caught off guard.
2014 · apichangelog.substack.com · its alternatives →
4
ApiContract▲82
AI platform detects, fixes & eliminates API breaking changes
2024 · apicontract.dev · its alternatives →
5
Visual Diffs▲95
Track UX changes with visual diffs on every deploy.
2015 · speedcurve.com · its alternatives →
6
Probely 2.0▲93
Quickly scan your website and fix vulnerabilities
2019 · probely.com · its alternatives →
7
apibeats▲93
Get notified on Slack when the API changes
2020 · apibeats.com · its alternatives →
8
ApiChecker▲104
Reliable uptime and performance monitoring for your services
2019 · its alternatives →
9DI
Diff.io▲194
2015 · diff.io · its alternatives →
10GN
Get notified when sites update their terms of service▲190
After reading about what happened with NightOwl yesterday [0], I thought about what it would take to be aware of things like that in the future. I created ToSNotify to automatically notify you when a website's terms change. A harder problem I've been thinking through is how to know which terms to track, since it'd be a pain to add every site I have an account with. One idea I had is to automatically get terms for apps you have installed from the app store. Any other ideas/feedback are appreciated! [0]: https://news.ycombinator.com/item?id=37052508
2023 · tosnotify.com · its alternatives →
11
Sonarly▲156
The AI that fixes prod autonomously
Mar 2026 · sonarly.com · its alternatives →
12
Apiwatch▲14
Keep track of the APIs you use.
2023 · its alternatives →
13
Changedetection.io detect changes in websites and JSON feeds▲147
Best and simplest tool for website change detection, web page monitoring, and website change alerts. Perfect for tracking content changes, price drops, restock alerts, and website defacement monitoring—all for free or enjoy our SaaS plan! - dgtlmoon/changedetection.io
2022 · github.com · its alternatives →
14
Recost▲130
Your API costs fully visible.
Apr 2026 · recost.dev · its alternatives →
15
Let Me Know When▲120
AI-Powered website URL monitoring
2024 · letmeknowwhen.app · its alternatives →
16
API Guard ▲7
Stop API disasters before they break production
2025 · apiguard.vercel.app · its alternatives →
17
Monitor website changes with AI▲94
Monitor any page for changes — without the false alarms. Describe what to watch in plain English, and Monity.ai alerts you only when it really changes.
2025 · monity.ai · its alternatives →
18
DepLog.dev▲7
Track dependency updates before they break your app
Jan 2026 · deplog.dev · its alternatives →
19
InfraDiff▲5
Know what changed in AWS — before it becomes a problem.
Jan 2026 · infradiff.com · its alternatives →
20
WatchPage▲3
Website Changes
Jun 2026 · watchpage.app · its alternatives →
21
api-diff▲1
Catch API contract drift before your users do
Sep 2026 · npmjs.com · its alternatives →
22
Callcounter▲62
Analytics for APIs - discover trends, bottlenecks, errors
2021 · its alternatives →
23
The Witness▲8
When a page updates, you understand why.
Feb 2026 · its alternatives →
24
Watched▲3
API-first website change detection with native MCP support
Jun 2026 · watchedapi.com · its alternatives →

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Ranked by how close each launch is in meaning, then by votes. Prices were read from each product’s own site when checked and can change. Refine with your own description →