Zillow, Tulia, Redfin etc. websites all can filter recent sales. Uses houses that have closed within the last 3 months and definitely under the last 6 months. You may have to look at sales listings and make an evaluation of whether it is comparable based on square footage, location/school district, acerage, etc. Might help to drive by a potential comp and look at the exterior. It helps if the sold listing still has interior photos posted on the websites -- but often interior photos are taken down shortly after closing.

My experience is you can get pretty close, especially if your house is a tract house with similar houses nearby that were built about the same time. If you truly have a unique house its a little harder to do the above.

For redfin, when you go to the property history, you frequently still can click on the sold or listed link and get the original listing, with interior pics.

Check the local newspapers real estate section. Ours lists houses that have sold. Addresses, names and prices. Also check with the town's tax assessor. They keep all types of info for what was built, what was sold, how much taxes are, etc. Our assessor just did a presentation to our selectmen/woman to let us know we are finally recovered from the real estate recession. We are back to where we were before the big dive. In our town we can get that info online. Picture of the house, layout, buyers and sellers names and how much it sold for. It is all public info. No need for a realtor.