HTTPS support for DBpedia APIs

I would like to be able to access DBpedia’s API services from my HTTPS-hosted web page, but it appears that there are only HTTP versions of the DBpedia API exposed. This causes a Mixed-Content security error in most modern browsers, and the typical solution is for the API provider to make their service available via HTTPS.

I’m trying to access the LDF service as described here: (note that this is HTTP)

But my website is HTTPS, so my browser prevents this security violation (Mixed Content).

I would like to know whether there is a HTTPS version of the above LDF API to DBpedia, and if someone could provide me the proper URL to access it.

If not, is there a plan to address this limitation? While I could use a proxy, it seems an unnecessary burden considering most browsers encourage HTTPS nowadays.


Thanks for spotting this, we are trying to consolidate research prototypes at the moment into these categories:

  • applications for download and self-deploy
  • shared services: high quality free services with no guaranteed sla
  • dedicated (paid)

I will ping Ruben who hosts LDF to get a statement.

Indeed. Good news is that we have scheduled HTTPS porting for all of our services this summer, including


@RubenVerborgh We are collecting services around the data currently manually.

Could you complete your record here:

You can check how it looks here:
updated every 30 min.

The examples below display the Beatles’ members using the formerBandMember predicate…

My hypothesis is that even if I access via https, it is returning metadata that points to the http version of, so that the subsequent requests from within comunica-browser.js will be to the http version, which will fail due to mixed-content errors.

I’m going to explore hacking the proxy option to the Comunica engine, so that it takes a function (optionally) instead of a prefix string. This function can rewrite the http into https prior to the subsequent requests. @RubenVerborgh if there is a better way, please let me know (or just tell me to wait longer for y’all to fix it).


This is indeed a problem on the server side, which we will fix.


In the meantime, the httpProxyHandler option to Comunica.newEngine().query() is a workaround I can use to get my work done when I’m using the programmatic API

const httpProxyHandler = {
  getProxy: function getProxy(request) {
    request.input = request.input.replace('', '');
    return request;

    httpProxyHandler: httpProxyHandler,
    sources: [
        type: '',
        value: ''

The server has been updated, so queries will work as expected.
Thanks again for reporting!


Same is happening with
In chrome it gives the error : net::ERR_CERT_DATE_INVALID

I think it is a certificate problem. In main domain, it is working without any error. (i.e.

I hope this will be fixed…

They have same maintenance issues try to access all day.

The dbpedia SPARQL endpoint service is up now. But the problem persists…
live.dbpedia/sparql is still having problems…

There was a hardware failure on over the weekend . New part will be installed tonight which should restore operations. I apologize for any inconvenience.

Thanks for looking into it.
Please also look into the certificate issue…
Thanks in advance.

@anandcv @valexande /CC @kurzum

Maintenance on has been completed successfully.

Issues with the certificate have been resolved as well.

Thank you for the quick resolution!
Works without any issues…

Were all the APIs not moved to https:? I see the linked data one seems to redirect from https: to http:

$ curl -I
HTTP/1.1 302 Moved Temporarily
Server: nginx/1.18.0
Date: Sun, 06 Dec 2020 14:33:20 GMT
Content-Type: text/html
Content-Length: 145
Connection: keep-alive

This means it can’t be accessed by browser scripts, as @doctorbud mentioned as the original post in this thread.

Note that the original forum post talked about which is a different API than the pages that @timbl checked.

On the current instance we only enabled https support on the /sparql endpoint to deal with web applications which need an https endpoint in order to use Ajax / CORS to get results from queries.

The DBpedia Association and OpenLink Software are currently testing a new database based on the new Databus technology which will soon replace the content. With the new database content, OpenLink will also enable https access on all endpoints under

A demo is currently available on

$ curl -I
HTTP/2 200 
date: Tue, 08 Dec 2020 15:25:52 GMT
content-type: application/rdf+xml; charset=UTF-8
content-length: 961476
vary: Accept-Encoding
server: Virtuoso/08.03.3319 (Linux) x86_64-generic-linux-glibc25  VDB
accept-ranges: bytes
expires: Tue, 15 Dec 2020 16:25:51 GMT
content-location: Massachusetts_Institute_of_Technology.xml
link: <>;rel="license",<>; rel="alternate"; type="application/rdf+xml"; title="Structured Descriptor Document (RDF/XML format)", <>; rel="alternate"; type="text/n3"; title="Structured Descriptor Document (N3/Turtle format)", <>; rel="alternate"; type="application/json"; title="Structured Descriptor Document (RDF/JSON format)", <>; rel="alternate"; type="application/atom+xml"; title="OData (Atom+Feed format)", <>; rel="alternate"; type="application/odata+json"; title="OData (JSON format)", <>; rel="alternate"; type="text/html"; title="XHTML+RDFa", <>; rel="", <>; rev="describedby", <>; rel="timegate"
content-disposition: filename=sparql_2020-12-08_15-25-52Z.rdf
strict-transport-security: max-age=15768000