diff --git a/reflection.json b/reflection.json
index e010ef02..adc8aa6f 100644
--- a/reflection.json
+++ b/reflection.json
@@ -18,11 +18,26 @@
   "allPublicMethods" : true,
   "allPublicFields" : true,
   "allPublicConstructors" : true
+}, {
+  "name" : "java.io.ByteArrayInputStream",
+  "allPublicMethods" : true,
+  "allPublicFields" : true,
+  "allPublicConstructors" : true
+}, {
+  "name" : "java.io.ByteArrayOutputStream",
+  "allPublicMethods" : true,
+  "allPublicFields" : true,
+  "allPublicConstructors" : true
 }, {
   "name" : "java.io.File",
   "allPublicMethods" : true,
   "allPublicFields" : true,
   "allPublicConstructors" : true
+}, {
+  "name" : "java.io.IOException",
+  "allPublicMethods" : true,
+  "allPublicFields" : true,
+  "allPublicConstructors" : true
 }, {
   "name" : "java.io.InputStream",
   "allPublicMethods" : true,
@@ -118,6 +133,31 @@
   "allPublicMethods" : true,
   "allPublicFields" : true,
   "allPublicConstructors" : true
+}, {
+  "name" : "java.net.HttpURLConnection",
+  "allPublicMethods" : true,
+  "allPublicFields" : true,
+  "allPublicConstructors" : true
+}, {
+  "name" : "java.net.URI",
+  "allPublicMethods" : true,
+  "allPublicFields" : true,
+  "allPublicConstructors" : true
+}, {
+  "name" : "java.net.URLDecoder",
+  "allPublicMethods" : true,
+  "allPublicFields" : true,
+  "allPublicConstructors" : true
+}, {
+  "name" : "java.net.URLEncoder",
+  "allPublicMethods" : true,
+  "allPublicFields" : true,
+  "allPublicConstructors" : true
+}, {
+  "name" : "java.net.UnknownHostException",
+  "allPublicMethods" : true,
+  "allPublicFields" : true,
+  "allPublicConstructors" : true
 }, {
   "name" : "java.nio.file.CopyOption",
   "allPublicMethods" : true,
@@ -288,6 +328,41 @@
   "allPublicMethods" : true,
   "allPublicFields" : true,
   "allPublicConstructors" : true
+}, {
+  "name" : "java.util.zip.DeflaterInputStream",
+  "allPublicMethods" : true,
+  "allPublicFields" : true,
+  "allPublicConstructors" : true
+}, {
+  "name" : "java.util.zip.GZIPInputStream",
+  "allPublicMethods" : true,
+  "allPublicFields" : true,
+  "allPublicConstructors" : true
+}, {
+  "name" : "java.util.zip.GZIPOutputStream",
+  "allPublicMethods" : true,
+  "allPublicFields" : true,
+  "allPublicConstructors" : true
+}, {
+  "name" : "java.util.zip.InflaterInputStream",
+  "allPublicMethods" : true,
+  "allPublicFields" : true,
+  "allPublicConstructors" : true
+}, {
+  "name" : "javax.xml.bind.DatatypeConverter",
+  "allPublicMethods" : true,
+  "allPublicFields" : true,
+  "allPublicConstructors" : true
+}, {
+  "name" : "sun.net.www.protocol.http.HttpURLConnection",
+  "allPublicMethods" : true,
+  "allPublicFields" : true,
+  "allPublicConstructors" : true
+}, {
+  "name" : "sun.net.www.protocol.http.HttpURLConnection$HttpInputStream",
+  "allPublicMethods" : true,
+  "allPublicFields" : true,
+  "allPublicConstructors" : true
 }, {
   "name" : "sun.nio.fs.UnixPath",
   "allPublicMethods" : true,
@@ -363,4 +438,47 @@
     "name" : "yield"
   } ],
   "name" : "java.lang.Thread"
+}, {
+  "allPublicConstructors" : true,
+  "allPublicFields" : true,
+  "methods" : [ {
+    "name" : "equals"
+  }, {
+    "name" : "getAuthority"
+  }, {
+    "name" : "getContent"
+  }, {
+    "name" : "getDefaultPort"
+  }, {
+    "name" : "getFile"
+  }, {
+    "name" : "getHost"
+  }, {
+    "name" : "getPath"
+  }, {
+    "name" : "getPort"
+  }, {
+    "name" : "getProtocol"
+  }, {
+    "name" : "getQuery"
+  }, {
+    "name" : "getRef"
+  }, {
+    "name" : "getUserInfo"
+  }, {
+    "name" : "hashCode"
+  }, {
+    "name" : "openConnection"
+  }, {
+    "name" : "openStream"
+  }, {
+    "name" : "sameFile"
+  }, {
+    "name" : "toExternalForm"
+  }, {
+    "name" : "toString"
+  }, {
+    "name" : "toURI"
+  } ],
+  "name" : "java.net.URL"
 } ]
\ No newline at end of file
diff --git a/script/compile b/script/compile
index 94cb69fa..ac925a5a 100755
--- a/script/compile
+++ b/script/compile
@@ -23,7 +23,9 @@ BABASHKA_VERSION=$(cat resources/BABASHKA_VERSION)
 # mkdir -p src/sci
 # cp -R /tmp/sci/src/* src
 
+lein with-profiles +reflection do run
 lein do clean, uberjar
+
 $NATIVE_IMAGE \
   -jar target/babashka-$BABASHKA_VERSION-standalone.jar \
   -H:Name=bb \
diff --git a/src/babashka/impl/classes.clj b/src/babashka/impl/classes.clj
index 987197f2..e24d2015 100644
--- a/src/babashka/impl/classes.clj
+++ b/src/babashka/impl/classes.clj
@@ -8,8 +8,11 @@
                       clojure.lang.LineNumberingPushbackReader
                       java.io.BufferedReader
                       java.io.BufferedWriter
+                      java.io.ByteArrayInputStream
+                      java.io.ByteArrayOutputStream
                       java.io.File
                       java.io.InputStream
+                      java.io.IOException
                       java.io.OutputStream
                       java.io.StringReader
                       java.io.StringWriter
@@ -29,6 +32,11 @@
                       java.lang.UNIXProcess$ProcessPipeOutputStream
                       java.lang.ProcessBuilder
                       java.lang.ProcessBuilder$Redirect
+                      java.net.URI
+                      java.net.HttpURLConnection
+                      java.net.UnknownHostException
+                      java.net.URLEncoder
+                      java.net.URLDecoder
                       java.nio.file.CopyOption
                       java.nio.file.FileAlreadyExistsException
                       java.nio.file.Files
@@ -62,7 +70,14 @@
                       java.util.Base64
                       java.util.Base64$Decoder
                       java.util.Base64$Encoder
+                      java.util.zip.InflaterInputStream
+                      java.util.zip.DeflaterInputStream
+                      java.util.zip.GZIPInputStream
+                      java.util.zip.GZIPOutputStream
+                      javax.xml.bind.DatatypeConverter
                       sun.nio.fs.UnixPath ;; included because of permission check
+                      sun.net.www.protocol.http.HttpURLConnection ;; needed for clj-http.lite
+                      sun.net.www.protocol.http.HttpURLConnection$HttpInputStream ;; needed for clj-http.lite
                       ]
    :custom-classes {'java.lang.Thread
                     {:allPublicConstructors true
@@ -100,7 +115,32 @@
                                {:name "sleep"}
                                {:name "start"}
                                {:name "toString"}
-                               {:name "yield"}]}}})
+                               {:name "yield"}]}
+                    'java.net.URL
+                    {:allPublicConstructors true
+                     :allPublicFields true
+                     ;; generated with `public-declared-method-names`, see in
+                     ;; `comment` below
+                     :methods [{:name "equals"}
+                               {:name "getAuthority"}
+                               {:name "getContent"}
+                               {:name "getDefaultPort"}
+                               {:name "getFile"}
+                               {:name "getHost"}
+                               {:name "getPath"}
+                               {:name "getPort"}
+                               {:name "getProtocol"}
+                               {:name "getQuery"}
+                               {:name "getRef"}
+                               {:name "getUserInfo"}
+                               {:name "hashCode"}
+                               {:name "openConnection"}
+                               {:name "openStream"}
+                               {:name "sameFile"}
+                               ;; not supported: {:name "setURLStreamHandlerFactory"}
+                               {:name "toExternalForm"}
+                               {:name "toString"}
+                               {:name "toURI"}]}}})
 
 (defmacro gen-class-map []
   (let [classes (concat (:default-classes classes)
@@ -148,4 +188,5 @@
          (vec)))
 
   (public-declared-method-names java.lang.UNIXProcess)
+  (public-declared-method-names java.net.URL)
   )
diff --git a/src/babashka/impl/clojure/core.clj b/src/babashka/impl/clojure/core.clj
index 896d06a2..a1a726df 100644
--- a/src/babashka/impl/clojure/core.clj
+++ b/src/babashka/impl/clojure/core.clj
@@ -5,6 +5,7 @@
 (def core-extras
   {'file-seq file-seq
    'agent agent
+   'instance? instance? ;; TODO: move to sci
    'send send
    'send-off send-off
    'promise promise
diff --git a/src/babashka/impl/clojure/java/io.clj b/src/babashka/impl/clojure/java/io.clj
index 59e9b1f2..88e7ec0c 100644
--- a/src/babashka/impl/clojure/java/io.clj
+++ b/src/babashka/impl/clojure/java/io.clj
@@ -3,6 +3,7 @@
 
 (def io-namespace
   {'as-relative-path io/as-relative-path
+   'as-url io/as-url
    'copy io/copy
    'delete-file io/delete-file
    'file io/file