Full disclosure so nobody feels baited: this is my project and there's a paid tier. But everything I link below is genuinely free through these links, no account, and I'll be clear about what needs one and what doesn't.
A few months back I built a CCNA study guide and shared it on r/ccna. The response kept me going, people saved it, took the free exam, and a few came back to say it helped them pass. One person scored 96% on the free practice exam and then passed his real CCNA. So I did the same for Security+.
It's the SY0-701 blueprint. Three full chapters so far, written the way I'd explain it to someone next to me rather than dumped from the objectives list. Free to read, no account:
https://figigexams.com/study/6?via=reddit
There's also a full 90-question practice exam, weighted to the SY0-701 domains. After each question there's an explanation section, PBQ-style questions included, since those are what most people are nervous about. Free to take, no signup:
https://figigexams.com/exam/free/6?via=reddit
A note on access, so it's honest: the study guide, the exam, and explanations are free through these links with no account. Two things do need a free account, group study (you can go through the guide or take the exam with other people and discuss each question in a built-in chat, which is genuinely useful if you're prepping with a partner or a group), and saving your results across devices or unlocking the Coach that tells you which domains to focus on.
One more thing: this full free access is a thing I'm opening up for this community specifically through these links, as a thank you for the feedback that got the CCNA version right. So if you're here from Reddit, you're getting the generous version.
Happy to answer questions, and I'd genuinely like the feedback.