Try Paraphrase API here

AI21 Studio's Paraphrase API offers access to our state-of-the-art paraphrasing engine. It has been fine-tuned specifically for paraphrasing. As a result, it's easier to integrate into your systems, and since it's optimized for this purpose, it's also more efficient (and therefore cheaper) than building it from scratch. This is also the engine behind Wordtune - so you know it's pretty awesome.

This API takes a piece of text and returns a list of paraphrases that convey the same meaning using different words. As a specialized API for paraphrasing, it contains features to enable you more control over the output: adjust the tone and style, with the choice of rewriting only parts of a text (while keeping the whole context).

Up to 10 suggested paraphrases

This API will return a list of up to 10 suggested paraphrases with every request.

{
  "style": "general",
  "text": "You only live once, but if you do it right, once is enough."
}

For example, here's a possible response for the request above:

{
  "id": "862829b2-29be-c86d-370e-db2f7f5dbf5b",
  "suggestions": [
    {
      "text": "One life is enough if you live it right."
    },
    {
      "text": "When you do it right, you only live once."
    },
    {
      "text": "Once is all you have, but if you do it right, once is enough."
    },
    {
      "text": "When you live right, you only need to live once."
    },
    {
      "text": "One life is enough if you live it right, but if you don't do it right, one life is not enough."
    },
    {
      "text": "The only chance you have to live is once, but if you live well, a once is enough."
    },
    {
      "text": "The only way to live is right, so if you do it right, once is enough."
    },
    {
      "text": "Once is enough if you live it right, but if you do it wrong, you'll regret it later."
    },
    {
      "text": "In life, you only live once, but if you do it right, once should be plenty."
    },
    {
      "text": "It takes only one life to live a fulfilling life, but if you do it right, one life is enough."
    }
  ]
}

Choose a style that fits your needs

You have the choice between 4 different styles:
general - explore fresh new ways to rephrase your sentences.
casual - convey a lighter and less serious tone for the right audience.
formal - present your words in a more professional way.
long - expand your sentences to give more detail, nuance and depth.
short - stick to word limits and convey your messages clearly and concisely.

Paraphrase within your span

You can paraphrase a specific span within the given text while keeping the surrounding text unchanged by specifying locations, using the startIndex and endIndex parameters. The API aims to rewrite exactly the requested span while avoiding disfluent suggestions. Satisfying both requirements is not always possible.