There are lots of search results for the search term "free violin sheet music". If you search for this ter on google there are over 430,000. I'm gathering you haven't got the time nor the inclination to surf through these, so here's a few websites to get you going. All of these sites are very extensive and excellent resources for free violin sheet music.

1. musicaviva.com

Large resource for free sheet music downloads including free violin sheet music and also free sheet music for piano, guitar, flute and more.

2. icking-music-archive.org
A community based sheet music resource founded by Werner Icking. There are pdfs on the site, however sheet music on the site is mainly generated by the music software MusiXTex, a music typesetting system based on TeX. You can download this system from the website.

3. gutenberg.org/wiki/Gutenberg:The_Sheet_Music_Project
The Project Gutenberg collection is a website produced by the assistance of tens of thousands of volunteers. Project Gutenberg volunteers have been engaging in digitizing public domain sheet music, using a variety of techniques, to enable study and performance. For the most part, the musical pieces created have been chamber music, with composers such as Brahms and Beethoven. Volunteers of this sheet music project have been turning public domain sheet music into digital form, to enable study and performance. Most pieces are chamber music with a focus on composers such as Brahms and Beethoven. Project Gutenberg gratefully accepts donations.

4. sibeliusmusic.com
Large sheet music portal with a huge collection of scores and sheet music. Many scores are free and some charge a small fee. You can register as a member and upload your own arrangements and/or compositions and open your own online sheet music shop. Just make sure you check arrangements before you perform them. The website uses a plug-in called Sibelius Scorch which is very cool.

5. violinsheetmusic.org
This site is not huge however it is an exceptionally tidy site that's very well laid out and without any fluff. The site offers printable free violin sheet music that has been scanned from public domain editions. There are some works with piano accompaniments too.