Check out the list below, each has it’s own description with a little review on what we think of the service. They are not in a set order so take a look at more than one before you settle on which to use.
Very nicely designed website and easy to use as well. You have to create a free account in order to start downloading the files. All clips are available in MP3 and some also available in WAV. Thousands to choose from split nicely in to categories and also tags.
Really nice site to use with thousands of great sounds. Create an account, navigate to sounds via the search box or tags, click on a sound title & download. Service is regularly maintained so they can be relied upon if you are a regular user. If you wish to support them you can also donate a small amount of money to them.
A very mature service which started way back in 2001. It is a very simple website to use with a traditional category system in place. Navigate to sounds you like, click the play button to here a preview, and right click on the title to download it. Clear notice on every page to ask you to NOT re-sell or re-license anything so please respect that.
Snother well estalished service. Not the best looking site but gives free access to lots of great sounds. Use search function to locate sounds, click to preview or right-click to save. Lots of languages covered as well in case your audience is from a specific region. Also now have a low-cost Android app available in Google Play.
Premium options are also available
If you have a bit of money to spend some companies also offer premium options where you can subscribe to packages or pay for individual files. Always do your homework before committing any money to it. If you are looking for voice overs you can also find people around the web who will record short voice-overs for very little money. Services like fiverr.com are great for hunting these kind of bargains. Ideal if you need an introduction to your Podcast to use each episode.
Below is a look at one of the premium services.
Super easy to use and really smart professionally designed site. Pick the category of sounds you like, choose relevant format to download. At the time of writing prices even at the most expensive are only $1.80 per sound, and economies of scale are also active as the more you need to lower the cost works out. They also have a separate service for music called StereoBot ideal if you are after longer tracks.