Omnistar has been in the affiliate software game since 2000 (before Shopify existed). They offer a big set of features and 24/7 support. Their full suite of e-commerce products are used by over 16,000 stores. Their entry level plans start at $47.95 but if you can swing the monthly fee, you should be impressed with their feature set and customer support. Here's my breakdown below.

Plans & Pricing

All plans include free setup, unlimited orders and sales volume, and 24/7 phone, e-mail, and live chat support. The bigger plans include more affiliate users and tracking requests, customizable forms, and timed or exit-intent pop-ups.

Basic – $47.95/mo for up to 200 affiliates and 20,000 tracking requests

Professional – $97.95/mo for up to 1,000 affiliates and 500,000 tracking requests

Premium – $147.95/mo for up to 5,000 affiliates and 1M tracking requests

Custom – Contact them for custom pricing if your number of affiliates exceeds 5k or your tracking requests exceed 1M.

Features

Unlimited: Orders, Sales Volume, Support

Limited: Plan dependent on number of affiliates and tracking requests

Affiliate Signup Page – You can customize a landing page hosted at Omnistar for your affiliates to sign up, or embed the sign-up form directly into your website.

Affiliate Recruitment – Omnistar offers tools to help convert customers into affiliates. They also have an Affiliate Importer tool if you're switching from a different software.

Track Affiliate Sales by URL: Yes (for the most part, this is standard among all services)

Customizable URL: Yes, you can customize the affiliate URL (ie: change the affiliate code from a random string of numbers/letters to “paul” for example).

Track by Discount Code: Yes you can track affiliate sales by coupon code. Very possible and not difficult, although a slightly less integrated process with Shopify than other apps as you'll need to install the tracking code manually into your store theme instead of via their app.

Track by Customer E-mail: No, you cannot permanently assign a customer to an affiliate.

Link to Individual Products: Yes, affiliates can link to any product or page on your site.

Sub IDs: Yes, used for tracking purposes.

Syncs with Shopify Refunds: No, if there's a refund, you have to manually remove the commission from the affiliate management dashboard.

Control Cookie Length: Yes, you can control the length of the cookie period.

Commission Type: You can reward affiliates with a Dollar Amount or Percentage of each sale. You can also compensate them with Gift Cards, Coupons, or Discounts.

Referral Contests – Omnistar has a unique affiliate contest feature to encourage referrals through a competition among affiliates. This feature lets you to reward the affiliate that sends the amount of leads or sales that you set to win the contest.

Recurring Commissions – You can offer a recurring commission to your affiliates with Omnistar.

Custom Commissions per SKU: Yes, you can have different commission offers per product.

Custom Commissions per Affiliate: Yes,  you can manually change the commission rate or structure for specific affiliates.

Only Pay For New Customers: No, there is no option to only pay affiliates for new customers. Returning customers whose sales were generated through an affiliate link are also paid a commission to the affiliate.

Vendor Payout (Multiple Tier): Omnistar offers a two-tier affiliate program. This allows you to have a “Parent Affiliate” who receive on-going commissions for referring “sub-affiliates”.

Multiple Stores w/ Single Affiliate Login: No, you cannot run more than one store through the same affiliate backend.

Payout Options: Paypal or Gift Cards (for your store)