curl the next few years - perhaps

Roadmap of things Daniel Stenberg and Steve Holme want to work on next. It is intended to serve as a guideline for others for information, feedback and possible participation.


Improve performance. Measurements and tests have shown that in several cases doing transfers over HTTP/2 can be notably slower than the same transfer done over HTTP/1. Some of that difference can be attributed the inefficient window size handling currently in use but there are probably more to be learned and worked on to optimize this.


The standardization process of QUIC has been taken to the IETF and can be followed on the IETF QUIC Mailing list. I'd like us to get on the bandwagon. Ideally, this would be done with a separate library/project to handle the binary/framing layer in a similar fashion to how HTTP/2 is implemented. This, to allow other projects to benefit from the work and to thus broaden the interest and chance of others to participate.

TLS 1.3

The new version of the TLS protocol is in the pipeline and will soon start to get used out in the wild. It offers some new interesting features and will need the TLS libraries to adapt and quite likely provide additional or modified APIs. libcurl needs to adapt accordingly.

HTTP cookies

Two cookie drafts have been adopted by the httpwg in IETF and we should support them as the popular browsers will as well:

Deprecate modification of ‘secure’ cookies from non-secure origins

Cookie Prefixes

Firefox bug report about secure cookies

SRV records

How to find services for specific domains/hosts.

HTTPS to proxy

To avoid network traffic to/from the proxy getting snooped on. There's a git branch in the public git repository for this that we need to make sure works for all TLS backends and then merge!


make sure there's an easy handle passed in to curl_formadd(), curl_formget() and curl_formfree() by adding replacement functions and deprecating the old ones to allow custom mallocs and more

Third-party SASL

Add support for third-party SASL libraries such as Cyrus SASL.

SASL authentication in LDAP


Simplify the SMTP email

Simplify the SMTP email interface so that programmers don't have to construct the body of an email that contains all the headers, alternative content, images and attachments - maintain raw interface so that programmers that want to do this can

email capabilities

Allow the email protocols to return the capabilities before authenticating. This will allow an application to decide on the best authentication mechanism

Win32 pthreads

Allow Windows threading model to be replaced by Win32 pthreads port

dynamic buffer size

Implement a dynamic buffer size to allow SFTP to use much larger buffers and possibly allow the size to be customizable by applications. Use less memory when handles are not in use?

New stuff - curl

  1. Embed a language interpreter (lua?). For that middle ground where curl isn’t enough and a libcurl binding feels “too much”. Build-time conditional of course.

  2. Simplify the SMTP command line so that the headers and multi-part content don't have to be constructed before calling curl


  1. build for windows (considered hard by many users)

  2. curl -h output (considered overwhelming to users)

  3. we have > 170 command line options, is there a way to redo things to simplify or improve the situation as we are likely to keep adding features/options in the future too

  4. docs (considered “bad” by users but how do we make it better?)

  • split up curl.1
  1. authentication framework (consider merging HTTP and SASL authentication to give one API for protocols to call)

  2. Perform some of the clean up from the TODO document, removing old definitions and such like that are currently earmarked to be removed years ago


  1. files as there is no point in maintaining two sets of Windows makefiles. Note: These are currently being used by the Windows autobuilds