This is an evolving/wip compilation of handy sites & tools for competitor monitoring & comparison (on a limited budget)!
Social Monitoring
Affordable tools to monitor for mentions of your brand, competitors, or keywords on various socials.
F5Bot: Free & easy to configure tool to monitor Reddit, Hacker News, and Lobsters for keyword mentions. Results delivered via email so best to set it up to a google group that you can switch to digests if it’s not time sensitive.
Syften: No free tier, but a very powerful tool that monitors Reddit, HN, Twitter, various Forums, and more with a paid subscription. Syften can also notify via Slack rather than just via email.
Google Alerts: Less social and more news oriented, but free, easy, and effective.
Ads libraries
Several ad platforms maintain libraries that let you see your competitors’ advertisements, over time. This can often reveal strategic insights about what’s working for them and what’s not (make sure to look at inactive ads, too) in attracting a similar ICP audience.
LinkedIn: Includes both in-feed and conversation ads (so ads sent as DMs)
Meta: Covers FB, Instagram, Audience Network, Messenger, etc.
Developer marketing specific
Niche but helpful - GitHub star, Stack Overflow trends, and NPM trends are all helpful benchmarks.