WProofreader HTTP API

Extend the grammar and spell check functionality of your application with WProofreader HTTP API. Gain developer access to WebSpellChecker robust proofreading engine via HTTP API requests.

Try demo

Multilingual sentence corrector

Proofread spelling and grammar, improve your writing style in 20+ languages. Enjoy spelling autocorrect and autocomplete suggestions.

AI paraphrasing tool

Try WProofreader AI writing assistant 🪄 Play with the size and style of your texts, summarize key ideas and proofread.



Data in transit is encrypted with TLS protocol. GDPR-compliant. On-premise deployment is for security-conscious businesses.

We love when our clients enjoy our products. So we take every client’s need as our own.


We respond within a business day to all sales and tech requests and provide guided installation in case it’s needed.


Develop a custom proofreading tool for your app or system. Test a set of grammar and spell checking commands, and additional parameters providing you with access to the engine capabilities.

Frequently asked questions

The on-premise licensing is particularly suitable for companies with enhanced security requirements, since it allows all the proofreading requests to be processed within your own servers. The cloud plans eliminate your infrastructure and maintenance costs for proofreading engine, ensuring quick start within your current setup.

If you still hesitate, feel free to get in touch with us. We will be happy to schedule a call with you to discuss the most suitable solution for you.

If you end up exceeding the limit, the service will stop working. However, our team monitors the usage, and notify customers beforehand with the proposal to purchase another set of words. In this case, the price depends on the potential customer usage (per year) and the price of the appropriate usage plan.

Please see the complete Terms of Service for the cloud services. Also, we have an extensive Privacy Policy in place to protect your and your end users’ texts. Please see the details here.

Please check the Software License Agreement which contains the complete terms and conditions for downloading, installing and using the on-premise version of the WebSpellChecker solutions.

According to Commercial License Fees and Warranties clauses of our standard Software License Agreement, you have an option to request a refund of your commercial server license up to 30 days after the original date of purchase. However, such a refund option is possible only in case WebSpellChecker software breaches the given warranty.

After the 30-day period after the original date of purchase, refunds will not be available. To request a refund within 30 days of payment, please contact our sales team.


By default, WebSpellChecker doesn’t offer any discounts. Our goal is to build reliable and quality products available at the best price and to treat every customer equally. The prices are available for everyone so there’s no guessing or uncertainty around what you’re buying and how much it costs.

We do offer our customers Data Processing Addendum, it forms a part of Terms of Service. Here you can find all the materials related to our commitment and compliance with GDPR.

HTTP API specific questions

A single API request is limited to 50KB of text, which equals 50K characters including spaces. If you plan to have larger requests, please consider splitting such requests into smaller chunks.

If you are holder of the on-premise solution, you can increase this limit using application server settings.