Hello. I've found this site, and I am sure here are people who find this useful: https://www.instantssl.com/free-ssl-certificate.html There you can get an SSL certificate for 90 days for free.
90 days is not bad, but 1 year is better Provided by startssl.com and works well for a friend of mine with his business web.
You can use startssl to get free ssl that is not a trial for 30-90 days as O-D-T also mentioned. Also you can apply for WoT status (Web of Trust Network, which is performed face-to-face in person by other members with notary status) member with startssl. Any person can participate and be a member of the startssl WoT. Getting that type of membership will allow you to get a certificate that you would require to pay for otherwise. Another option would be to use cloudflare for extended security among other features and a free shared certificate that comes with the free membership.