diff --git a/include/fluent-bit/flb_api.h b/include/fluent-bit/flb_api.h
index 0559a5b2e58..4b87adde413 100644
--- a/include/fluent-bit/flb_api.h
+++ b/include/fluent-bit/flb_api.h
@@ -22,6 +22,7 @@
 
 #include <fluent-bit/flb_info.h>
 #include <fluent-bit/flb_output.h>
+#include <fluent-bit/flb_custom.h>
 
 struct flb_api {
     const char *(*output_get_property) (const char *, struct flb_output_instance *);
@@ -33,6 +34,11 @@ struct flb_api {
     void (*log_print) (int, const char*, int, const char*, ...);
     int (*input_log_check) (struct flb_input_instance *, int);
     int (*output_log_check) (struct flb_output_instance *, int);
+
+    /* To preserve ABI, we need to add these APIs after the
+     * input/output definitions. */
+    const char *(*custom_get_property) (const char *, struct flb_custom_instance *);
+    int (*custom_log_check) (struct flb_custom_instance *, int);
 };
 
 #ifdef FLB_CORE
diff --git a/include/fluent-bit/flb_custom.h b/include/fluent-bit/flb_custom.h
index 4c296f8ff04..c589e90f411 100644
--- a/include/fluent-bit/flb_custom.h
+++ b/include/fluent-bit/flb_custom.h
@@ -31,9 +31,20 @@
 #define FLB_CUSTOM_NET_CLIENT   1   /* custom may use upstream net.* properties  */
 #define FLB_CUSTOM_NET_SERVER   2   /* custom may use downstream net.* properties  */
 
+/* Custom plugin types */
+#define FLB_CUSTOM_PLUGIN_CORE   0
+#define FLB_CUSTOM_PLUGIN_PROXY  1
+
 struct flb_custom_instance;
 
 struct flb_custom_plugin {
+    /*
+     * The type defines if this is a core-based plugin or it's handled by
+     * some specific proxy.
+     */
+    int type;
+    void *proxy;
+
     int flags;             /* Flags (not available at the moment */
     char *name;            /* Custom plugin short name           */
     char *description;     /* Description                        */
@@ -96,5 +107,6 @@ int flb_custom_plugin_property_check(struct flb_custom_instance *ins,
 int flb_custom_init_all(struct flb_config *config);
 void flb_custom_set_context(struct flb_custom_instance *ins, void *context);
 void flb_custom_instance_destroy(struct flb_custom_instance *ins);
+int flb_custom_log_check(struct flb_custom_instance *ins, int l);
 
 #endif
diff --git a/include/fluent-bit/flb_plugin_proxy.h b/include/fluent-bit/flb_plugin_proxy.h
index 97ceb7ff5d2..3eb885562b1 100644
--- a/include/fluent-bit/flb_plugin_proxy.h
+++ b/include/fluent-bit/flb_plugin_proxy.h
@@ -28,6 +28,7 @@
 /* Plugin Types */
 #define FLB_PROXY_INPUT_PLUGIN     1
 #define FLB_PROXY_OUTPUT_PLUGIN    2
+#define FLB_PROXY_CUSTOM_PLUGIN    3
 
 /* Proxies available */
 #define FLB_PROXY_GOLANG          11
diff --git a/src/flb_api.c b/src/flb_api.c
index c11c1712c28..e7e84f349f8 100644
--- a/src/flb_api.c
+++ b/src/flb_api.c
@@ -24,6 +24,7 @@
 
 #include <fluent-bit/flb_input.h>
 #include <fluent-bit/flb_output.h>
+#include <fluent-bit/flb_custom.h>
 
 struct flb_api *flb_api_create()
 {
@@ -37,6 +38,7 @@ struct flb_api *flb_api_create()
 
     api->output_get_property = flb_output_get_property;
     api->input_get_property = flb_input_get_property;
+    api->custom_get_property = flb_custom_get_property;
 
 #ifdef FLB_HAVE_METRICS
     api->output_get_cmt_instance = flb_output_get_cmt_instance;
@@ -46,6 +48,7 @@ struct flb_api *flb_api_create()
     api->log_print = flb_log_print;
     api->input_log_check = flb_input_log_check;
     api->output_log_check = flb_output_log_check;
+    api->custom_log_check = flb_custom_log_check;
 
     return api;
 }
diff --git a/src/flb_custom.c b/src/flb_custom.c
index 94b6c180444..80ec9484b22 100644
--- a/src/flb_custom.c
+++ b/src/flb_custom.c
@@ -27,6 +27,7 @@
 #include <fluent-bit/flb_pack.h>
 #include <fluent-bit/flb_metrics.h>
 #include <fluent-bit/flb_utils.h>
+#include <fluent-bit/flb_plugin_proxy.h>
 #include <fluent-bit/flb_upstream.h>
 #include <fluent-bit/flb_downstream.h>
 #include <chunkio/chunkio.h>
@@ -183,6 +184,24 @@ struct flb_custom_instance *flb_custom_new(struct flb_config *config,
     snprintf(instance->name, sizeof(instance->name) - 1,
              "%s.%i", plugin->name, id);
 
+    if (plugin->type == FLB_CUSTOM_PLUGIN_CORE) {
+        instance->context = NULL;
+    }
+    else {
+        struct flb_plugin_proxy_context *ctx;
+
+        ctx = flb_calloc(1, sizeof(struct flb_plugin_proxy_context));
+        if (!ctx) {
+            flb_errno();
+            flb_free(instance);
+            return NULL;
+        }
+
+        ctx->proxy = plugin->proxy;
+
+        instance->context = ctx;
+    }
+
     instance->id    = id;
     instance->alias = NULL;
     instance->p     = plugin;
@@ -352,3 +371,15 @@ void flb_custom_set_context(struct flb_custom_instance *ins, void *context)
 {
     ins->context = context;
 }
+
+/* Check custom plugin's log level.
+ * Not for core plugins but for Golang plugins.
+ * Golang plugins do not have thread-local flb_worker_ctx information. */
+int flb_custom_log_check(struct flb_custom_instance *ins, int l)
+{
+    if (ins->log_level < l) {
+        return FLB_FALSE;
+    }
+
+    return FLB_TRUE;
+}
diff --git a/src/flb_plugin_proxy.c b/src/flb_plugin_proxy.c
index c8f318afbbd..018674ed992 100644
--- a/src/flb_plugin_proxy.c
+++ b/src/flb_plugin_proxy.c
@@ -33,6 +33,7 @@
 #include <fluent-bit/flb_utils.h>
 #include <fluent-bit/flb_plugin_proxy.h>
 #include <fluent-bit/flb_input_log.h>
+#include <fluent-bit/flb_custom.h>
 
 /* Proxies */
 #include "proxy/go/go.h"
@@ -422,6 +423,42 @@ static int flb_proxy_register_input(struct flb_plugin_proxy *proxy,
     return 0;
 }
 
+int flb_proxy_custom_cb_init(struct flb_custom_instance *c_ins,
+                             struct flb_config *config, void *data);
+
+static int flb_proxy_custom_cb_exit(void *custom_context, 
+                                    struct flb_config *config);
+
+static int flb_proxy_register_custom(struct flb_plugin_proxy *proxy,
+                                     struct flb_plugin_proxy_def *def,
+                                     struct flb_config *config)
+{
+    struct flb_custom_plugin *custom;
+
+    custom = flb_calloc(1, sizeof(struct flb_custom_plugin));
+    if (!custom) {
+        flb_errno();
+        return -1;
+    }
+
+    /* Plugin registration */
+    custom->type  = FLB_CUSTOM_PLUGIN_PROXY;
+    custom->proxy = proxy;
+    custom->flags = def->flags;
+    custom->name  = flb_strdup(def->name);
+    custom->description = def->description;
+    mk_list_add(&custom->_head, &config->custom_plugins);
+
+    /*
+     * Set proxy callbacks: external plugins which are not following
+     * the core plugins specs, have a different callback approach, so
+     * we put our proxy-middle callbacks to do the translation properly.
+     */
+    custom->cb_init = flb_proxy_custom_cb_init;
+    custom->cb_exit = flb_proxy_custom_cb_exit;
+    return 0;
+}
+
 void *flb_plugin_proxy_symbol(struct flb_plugin_proxy *proxy,
                               const char *symbol)
 {
@@ -487,6 +524,9 @@ int flb_plugin_proxy_register(struct flb_plugin_proxy *proxy,
         }
         else if (def->type == FLB_PROXY_INPUT_PLUGIN) {
             ret = proxy_go_input_register(proxy, def);
+        } 
+        else if (def->type == FLB_PROXY_CUSTOM_PLUGIN) {
+            ret = proxy_go_custom_register(proxy, def);
         }
 #endif
     }
@@ -501,6 +541,9 @@ int flb_plugin_proxy_register(struct flb_plugin_proxy *proxy,
         else if (def->type == FLB_PROXY_INPUT_PLUGIN) {
             flb_proxy_register_input(proxy, def, config);
         }
+        else if (def->type == FLB_PROXY_CUSTOM_PLUGIN) {
+            flb_proxy_register_custom(proxy, def, config);
+        }
     }
 
     return 0;
@@ -616,3 +659,51 @@ int flb_plugin_proxy_set(struct flb_plugin_proxy_def *def, int type,
 
     return 0;
 }
+
+int flb_proxy_custom_cb_init(struct flb_custom_instance *c_ins,
+                             struct flb_config *config, void *data)
+{
+    int ret = -1;
+    struct flb_plugin_proxy_context *pc;
+    struct flb_plugin_proxy *proxy;
+
+    pc = (struct flb_plugin_proxy_context *)(c_ins->context);
+    proxy = pc->proxy;
+
+    /* Before to initialize, set the instance reference */
+    pc->proxy->instance = c_ins;
+
+    if (proxy->def->proxy == FLB_PROXY_GOLANG) {
+#ifdef FLB_HAVE_PROXY_GO
+        ret = proxy_go_custom_init(proxy);
+#endif
+    }
+
+    if (ret == -1) {
+        flb_error("[custom] could not initialize '%s' plugin",
+                  c_ins->p->name);
+        return -1;
+    }
+
+    return 0;
+}
+
+int flb_proxy_custom_cb_exit(void *custom_context, 
+                             struct flb_config *config)
+{
+    int ret = -1;
+    struct flb_plugin_proxy_context *ctx = custom_context;
+    struct flb_plugin_proxy *proxy = (ctx->proxy);
+    if (!custom_context) {
+        return ret;
+    }
+
+    if (proxy->def->proxy == FLB_PROXY_GOLANG) {
+#ifdef FLB_HAVE_PROXY_GO
+        ret = proxy_go_custom_destroy(ctx);
+#endif
+    }
+
+    flb_free(ctx);
+    return ret;
+}
diff --git a/src/proxy/go/go.c b/src/proxy/go/go.c
index 540005a8d9d..2045124df2c 100644
--- a/src/proxy/go/go.c
+++ b/src/proxy/go/go.c
@@ -21,6 +21,7 @@
 #include <fluent-bit/flb_config.h>
 #include <fluent-bit/flb_plugin_proxy.h>
 #include <fluent-bit/flb_output.h>
+#include <fluent-bit/flb_custom.h>
 #include "./go.h"
 
 /*
@@ -41,7 +42,7 @@
  *
  *      - name: shortname of the plugin.
  *      - description: plugin description.
- *      - type: input, output, filter, whatever.
+ *      - type: input, output, filter, custom, whatever.
  *      - proxy: type of proxy e.g. GOLANG
  *      - flags: optional flags, not used by Go plugins at the moment.
  *
@@ -286,3 +287,87 @@ void proxy_go_input_unregister(void *data) {
     flb_free(plugin->name);
     flb_free(plugin);
 }
+
+int proxy_go_custom_register(struct flb_plugin_proxy *proxy,
+                            struct flb_plugin_proxy_def *def)
+{
+    struct flbgo_custom_plugin *plugin;
+
+    plugin = flb_malloc(sizeof(struct flbgo_custom_plugin));
+    if (!plugin) {
+        flb_errno();
+        return -1;
+    }
+
+    /*
+     * Lookup the entry point function:
+     *
+     * - FLBPluginInit
+     * - FLBPluginExit
+     *
+     * note: registration callback FLBPluginRegister() is resolved by the
+     * parent proxy interface.
+     */
+
+    plugin->cb_init  = flb_plugin_proxy_symbol(proxy, "FLBPluginInit");
+    if (!plugin->cb_init) {
+        flb_error("[go proxy]: could not load FLBPluginInit symbol");
+        flb_free(plugin);
+        return -1;
+    }
+
+    plugin->cb_exit  = flb_plugin_proxy_symbol(proxy, "FLBPluginExit");
+
+    plugin->name = flb_strdup(def->name);
+
+    /* This Go plugin context is an opaque data for the parent proxy */
+    proxy->data = plugin;
+
+    return 0;
+}
+
+int proxy_go_custom_init(struct flb_plugin_proxy *proxy)
+{
+    int ret = 0;
+    struct flbgo_custom_plugin *plugin = proxy->data;
+
+    /* set the API */
+    plugin->api   = proxy->api;
+    plugin->i_ins = proxy->instance;
+    /* In order to avoid having the whole instance as part of the ABI we */
+    /* copy the context pointer into the plugin. */
+    plugin->context = ((struct flb_custom_instance *)proxy->instance)->context;
+
+    ret = plugin->cb_init(plugin);
+    if (ret <= 0) {
+        flb_error("[go proxy]: plugin '%s' failed to initialize",
+                  plugin->name);
+        flb_free(plugin);
+        return -1;
+    }
+
+    return ret;
+}
+
+int proxy_go_custom_destroy(struct flb_plugin_proxy_context *ctx)
+{
+    int ret = 0;
+    struct flbgo_custom_plugin *plugin;
+
+    plugin = (struct flbgo_custom_plugin *) ctx->proxy->data;
+
+    if (plugin->cb_exit) {
+        ret = plugin->cb_exit();
+    }
+
+    return ret;
+}
+
+void proxy_go_custom_unregister(void *data) {
+    struct flbgo_custom_plugin *plugin;
+
+    plugin = (struct flbgo_custom_plugin *) data;
+    flb_free(plugin->name);
+    flb_free(plugin);
+}
+
diff --git a/src/proxy/go/go.h b/src/proxy/go/go.h
index eed328e24bf..0d011bc323a 100644
--- a/src/proxy/go/go.h
+++ b/src/proxy/go/go.h
@@ -48,6 +48,16 @@ struct flbgo_input_plugin {
     int (*cb_exit)();
 };
 
+struct flbgo_custom_plugin {
+    char *name;
+    void *api;
+    void *i_ins;
+    struct flb_plugin_proxy_context *context;
+
+    int (*cb_init)();
+    int (*cb_exit)();
+};
+
 int proxy_go_output_register(struct flb_plugin_proxy *proxy,
                              struct flb_plugin_proxy_def *def);
 
@@ -69,4 +79,12 @@ int proxy_go_input_cleanup(struct flb_plugin_proxy *ctx,
                            void *allocated_data);
 int proxy_go_input_destroy(struct flb_plugin_input_proxy_context *ctx);
 void proxy_go_input_unregister(void *data);
+
+int proxy_go_custom_register(struct flb_plugin_proxy *proxy,
+                             struct flb_plugin_proxy_def *def);
+
+int proxy_go_custom_init(struct flb_plugin_proxy *proxy);
+
+int proxy_go_custom_destroy(struct flb_plugin_proxy_context *ctx);
+void proxy_go_custom_unregister(void *data);
 #endif