diff --git a/processor/src/main/kotlin/org/ethereum/lists/chains/Main.kt b/processor/src/main/kotlin/org/ethereum/lists/chains/Main.kt
index 8d16e129..c82bd729 100644
--- a/processor/src/main/kotlin/org/ethereum/lists/chains/Main.kt
+++ b/processor/src/main/kotlin/org/ethereum/lists/chains/Main.kt
@@ -320,9 +320,11 @@ fun checkChain(chainFile: File, connectRPC: Boolean, verbose: Boolean = false) {
             }
 
             if (url.endsWith("/")) {
-                throw (ExplorerCannotEndInSlash())
+                throw ExplorerCannotEndInSlash()
             }
 
+            url.checkString("Explorer URL")
+
             if (explorer["standard"] != "EIP3091" && explorer["standard"] != "none") {
                 throw (ExplorerStandardMustBeEIP3091OrNone())
             }
@@ -360,9 +362,7 @@ fun checkChain(chainFile: File, connectRPC: Boolean, verbose: Boolean = false) {
                 throw FaucetMustBeString()
             }
 
-            if (it.isBlank()) {
-                throw FaucetMustBeString()
-            }
+            it.checkString("Faucet URL")
         }
 
     }
@@ -376,6 +376,7 @@ fun checkChain(chainFile: File, connectRPC: Boolean, verbose: Boolean = false) {
                 throw RedFlagMustBeString()
             }
 
+            it.checkString("Red flag")
             if (!allowedRedFlags.contains(it))
                 throw (InvalidRedFlags(it))
         }
@@ -427,11 +428,10 @@ fun checkChain(chainFile: File, connectRPC: Boolean, verbose: Boolean = false) {
         (jsonObject["rpc"] as List<*>).forEach {
             if (it !is String) {
                 throw (RPCMustBeListOfStrings())
-            } else if (it.isBlank()) {
-                throw (RPCCannotBeEmpty())
             } else if (rpcPrefixes.none { prefix -> it.startsWith(prefix) }) {
                 throw (InvalidRPCPrefix(it))
             } else {
+                it.checkString("RPC URL")
                 if (connectRPC) {
                     var chainId: BigInteger? = null
                     try {
@@ -457,6 +457,16 @@ fun checkChain(chainFile: File, connectRPC: Boolean, verbose: Boolean = false) {
     }
 }
 
+private fun String.checkString(which: String) {
+    if (isBlank()) {
+        throw StringCannotBeBlank(which)
+    }
+
+    if (trim() != this) {
+        throw StringCannotHaveExtraSpaces(which)
+    }
+}
+
 fun String.normalizeName() = replace(" ", "").uppercase()
 
 /*
diff --git a/processor/src/main/kotlin/org/ethereum/lists/chains/model/Exceptions.kt b/processor/src/main/kotlin/org/ethereum/lists/chains/model/Exceptions.kt
index 997cef19..5d263f1c 100644
--- a/processor/src/main/kotlin/org/ethereum/lists/chains/model/Exceptions.kt
+++ b/processor/src/main/kotlin/org/ethereum/lists/chains/model/Exceptions.kt
@@ -22,6 +22,9 @@ class ExplorersMustBeArray: Exception("explorers must be an array")
 class ExplorerMustHaveName: Exception("Explorer must have name")
 class ExplorerMustWithHttpsOrHttp: Exception("Explorer have url starting with https:// or http://")
 class ExplorerCannotEndInSlash: Exception("Explorer cannot have a slash on the end")
+class StringCannotBeBlank(which: String): Exception("$which cannot be blank")
+
+class StringCannotHaveExtraSpaces(which: String): Exception("$which cannot have leading or tailing spaces")
 class ExplorerStandardMustBeEIP3091OrNone: Exception("explorer standard must be 'none' or 'EIP3091'")
 class ParentHasInvalidType(type: String?): Exception("Parent has invalid type $type - only L2 or shard allowed")
 class RedFlagsMustBeArray: Exception("redFlags not an array")
diff --git a/processor/src/test/resources/test_chains/invalid/sameshortname/eip155-5.json b/processor/src/test/resources/test_chains/invalid/sameshortname/eip155-5.json
index 82d9966e..5b24c243 100644
--- a/processor/src/test/resources/test_chains/invalid/sameshortname/eip155-5.json
+++ b/processor/src/test/resources/test_chains/invalid/sameshortname/eip155-5.json
@@ -3,7 +3,7 @@
   "chain": "ETH",
   "rpc": [
     "https://rpc.goerli.mudit.blog/",
-    "https://rpc.slock.it/goerli ",
+    "https://rpc.slock.it/goerli",
     "https://goerli.prylabs.net"
   ],
   "faucets": [
diff --git a/processor/src/test/resources/test_chains/valid/eip155-5.json b/processor/src/test/resources/test_chains/valid/eip155-5.json
index 3a5b5851..4f8e394b 100644
--- a/processor/src/test/resources/test_chains/valid/eip155-5.json
+++ b/processor/src/test/resources/test_chains/valid/eip155-5.json
@@ -3,7 +3,7 @@
   "chain": "ETH",
   "rpc": [
     "https://rpc.goerli.mudit.blog/",
-    "https://rpc.slock.it/goerli ",
+    "https://rpc.slock.it/goerli",
     "https://goerli.prylabs.net"
   ],
   "faucets": [