GReader API doc and improvements (#4763)

* GReader API doc and improvements
#fix https://github.com/FreshRSS/FreshRSS/issues/4762

* Minor slash

* HTTPS for web.archive.org

1 files changed, 31 insertions, 2 deletions

diff --git a/docs/en/developers/06_GoogleReader_API.md b/docs/en/developers/06_GoogleReader_API.md
index 4d35a6c3f..5a42dbb66 100644
--- a/docs/en/developers/06_GoogleReader_API.md
+++ b/docs/en/developers/06_GoogleReader_API.md
@@ -1,7 +1,8 @@
 # FreshRSS - Google Reader compatible API implementation
 
 See [Mobile access](../users/06_Mobile_access.md) for general aspects of API access.
-Additionally [page about our Fever compatible API](06_Fever_API.md) for another possibility.
+
+See also the [page about our Fever compatible API](06_Fever_API.md) for another possibility (less powerful).
 
 ## RSS clients
 
@@ -23,7 +24,7 @@ Then point your mobile application to the `greader.php` address (e.g. `https://f
 
 | App                                                                                | Platform            | License                                            |
 |:----------------------------------------------------------------------------------:|:-------------------:|:--------------------------------------------------------:|
-|[News+](https://github.com/noinnion/newsplus/blob/master/apk/NewsPlus_202.apk) with [News+ Google Reader extension](https://github.com/noinnion/newsplus/blob/master/apk/GoogleReaderCloneExtension_101.apk) |Android|Closed Source (Free)|
+|[News+](https://github.com/noinnion/newsplus/blob/master/apk/NewsPlus_202.apk) with [News+ Google Reader extension](https://github.com/noinnion/newsplus/blob/master/apk/GoogleReaderCloneExtension_101.apk) |Android|Closed Source (Free), [partially open source](https://github.com/noinnion/newsplus/blob/master/extensions/GoogleReaderCloneExtension/src/com/noinnion/android/newsplus/extension/google_reader/GoogleReaderClient.java)|
 |[FeedMe 3.5.3+](https://play.google.com/store/apps/details?id=com.seazon.feedme) |Android                  |Closed Source (Free)                                             |
 |[EasyRSS](https://github.com/Alkarex/EasyRSS)                          |Android                |[GPLv3](https://github.com/Alkarex/EasyRSS/blob/master/license.txt) ([F-Droid](https://f-droid.org/packages/org.freshrss.easyrss/))|
 |[Readrops](https://github.com/readrops/Readrops) |Android                  |[GPLv3](https://github.com/readrops/Readrops/blob/develop/LICENSE)                                             |
@@ -36,6 +37,8 @@ Then point your mobile application to the `greader.php` address (e.g. `https://f
 |[Reeder](https://www.reederapp.com/)                           |macOS, iOS                |Closed Source                                              |
 |[FreshRSS-Notify](https://addons.mozilla.org/firefox/addon/freshrss-notify-webextension/)                           |Firefox                |Open Source                                              |
 
+> ℹ️ See a [better table of compatible clients in our main Readme](https://github.com/FreshRSS/FreshRSS/blob/edge/README.md#apis--native-apps).
+
 ## Google Reader compatible API
 
 Examples of basic queries:
@@ -65,3 +68,29 @@ curl -H "Authorization:GoogleLogin auth=alice/8e6845e089457af25303abc6f53356eb60
 curl -s -H "Authorization:GoogleLogin auth=alice/8e6845e089457af25303abc6f53356eb60bdb5f8" \
   'https://freshrss.example.net/api/greader.php/reader/api/0/stream/contents/reading-list' | jq .
 ```
+
+* [Source code of our API implementation](https://github.com/FreshRSS/FreshRSS/blob/edge/p/api/greader.php)
+
+### API documentation from the original Google Reader
+
+* [By Daniel Arowser](https://web.archive.org/web/20130710044440/http://undoc.in/api.html) ([source](https://github.com/arowser/google-reader-api))
+* [By Martin Doms](https://web.archive.org/web/20210126115837/https://blog.martindoms.com/2009/10/16/using-the-google-reader-api-part-2/)
+* [By Nick Bradbury](https://inessential.com/2013/03/14/google_reader_api_documentation)
+* [By Niall Kennedy](https://web.archive.org/web/20170426184845/http://www.niallkennedy.com/blog/2005/12/google-reader-api.html)
+* [By Mihai Parparita](https://web.archive.org/web/20140919042419/http://code.google.com/p/google-reader-api/w/list) ([source](https://github.com/mihaip/google-reader-api))
+
+### API documentation from other compatible clients
+
+* [FeedHQ](https://feedhq.readthedocs.io/en/latest/api/index.html)
+* [Inoreader](https://www.inoreader.com/developers/)
+* [The Old Reader](https://github.com/theoldreader/api)
+* [pyrfeed](http://code.google.com/p/pyrfeed/wiki/GoogleReaderAPI)
+* [BazQux](https://github.com/bazqux/bazqux-api)
+
+### Synchronisation strategy
+
+> ℹ️ If you are maintaining a client or planning to develop a new one, please read carefully the following pieces of advice,
+as many clients start by having a very inneficient synchronisation strategy.
+
+* [*Synchronisation recommendation* by Alkarex](https://github.com/FreshRSS/FreshRSS/issues/2566#issuecomment-541317776)
+* [*The Right Way to Sync* by BazQux](https://github.com/bazqux/bazqux-api#user-content-the-right-way-to-sync)