Has a 250,000 words monthly limit on the “Turing Spinner” and a 2,500,000 words monthly limit on the “Standard Spinner”. Anything above that will be charged additionally ($10 per 1,000,000 words for the “Standard Spinner”, and $3 per 10,000 for the “Turing Spinner”). However, they do offer custom plans for heavy API users – all you need to do is contact them.
Spin Rewriter integrates with almost any SEO software. This allows you to post high quality articles quickly and easily. The only drawback is that you only get something like 300 API requests every 24 hours. You can quickly burn through this if you’re doing multiple campaigns. The developer does not currently offer a plan for heavy API users but maybe they will in the future.