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What is the Nilas Sync Engine and how can I use it?

The Nilas Sync Engine is the core of the Nilas platform. It's the primary interface with mail providers, used to sync mail and perform actions. It also exposes a beautiful modern JSON API that allows developers to quickly build email apps.

The code to this is currently available as open source free software that can be run by developers on any service. The Nilas Developer Program provides a fully managed and scalable service for production deployment. Sign up here.

To set up a development VM, see the installation instructions. We also provide pre-built SDKs for iOS and JavaScript to help you get started building apps. Full details on this and more can be found in the Nilas API Developer Documentation.

Why use Nilas instead of the Gmail API?

  • Nilas is open source, like Ruby on Rails, so you can run it yourself.
  • Nilas supports many providers, including Gmail, Yahoo, and Hotmail/, with plans to quickly add more. The Nilas Developer Program also supports Microsoft Exchange for enterprise users. You can build once for users everywhere.
  • If you find a bug in Nilas, you can submit a pull request and help fix it. If you have an idea for a feature, you can fork Nilas to add it.
  • Nilas is an email company. Google is an advertising company. This product is our focus, and will not be "discontinued" unexpectedly.

Do I need to run Nilas myself?

Currently, yes. If you are interested in the managed SaaS version, please request early-access to the Nilas Developer Program. We're rolling this product out slowly to ensure stability and scalability, and plan to make it available soon to all developers worldwide.

I started a sync—how long does it take to see mail data?

When you link an account to Nilas, it could take anywhere from a few minutes to a few days to build a complete cache of your mailbox. However, the Sync Engine is designed to pull recent messages first, so you should be able to get going quickly. Total sync time will be dependent on factors like total number of messages, your network bandwidth, processing power, and email provider's throttling.

Why does Nilas store mail data?

Nilas stores a local copy of your mailbox in order to provide fast and efficient access to messages, threads, and attachments. Mutable operations will update the local datastore immediately, and queue changes to sync back to your mail provider. This design is necessary in order to achieve the level of performance expected on modern developer platforms.

Why is there no authentication in the development VM?

For the sake of simplicity and setup speed, the development VM does not include any authentication or permission. For developing with sensitive data, we encourage developers to add their own protection, such as only running Nilas on a local machine or behind a controlled firewall.

Note that passwords and OAuth tokens are stored unencrypted in the local MySQL data store on disk. This is intentional, for the same reason as above.

How is Nilas different from Mailgun or Sendgrid?

Nilas allows you to access mail data inside the mailboxes of your users. For example, you could use Nilas to build an app showing detail from all the flight confirmation messages a user received last year. Transactional mail services like Mailgun, Sendgrid, or Amazon SES are an interface for sending mail from your app's address (e.g.:

When should I use the Nilas API?

You can use Nilas to replace nearly all the functionality of IMAP and SMTP. Nilas makes it easy to build anything from a simple notification hook to a full-fledged email client for your users.

How does this compare to the Gmail API?

Gmail offers a modern, restful API, but it is closed platform. Applications built on the Gmail API will only work with Gmail.

Nilas is designed to be easily extensible to all email providers. The open source license means that developers are free to run the Nilas Sync Engine anywhere, and build any sort of API integration they please.

Unanswered Questions?

Visit the Developer Documentation for more detailed technical answers, or shoot us an email at You can also chat with us on IRC. We hang out in ##nilas on