Wikipedia
A general encyclopaedia, useful mainly for its citations.
Cost
Completely free
Free, non-profit, no ads.
Open source
Yes
The code is public. Anyone can inspect it, and it cannot be taken away from you.
Your data
Goes to their servers
Your files and text are sent to the company running the service.
Use it for this
Orienting yourself in an unfamiliar topic and finding primary sources in the references.
Do not use it for this
Citing directly in serious work. Follow its references to the actual sources.
A moment where you would reach for it
Reading the overview, then scrolling to References and reading what it was built from.
How hard is it to pick up?
Anyone can use this on day one.
Other things that do this job
No tool is best at everything. These solve a similar problem, with different trade-offs.
About this entry
Checked on 1 Sept 2026. Prices and free limits change without warning, and often quietly. Treat everything above as a starting point and confirm on the official site before you rely on it.
Nothing here is sponsored. A tool appears because it solves a real problem, not because someone paid for it to be listed.