diff --git a/package.json b/package.json
index 986e388..901597d 100644
--- a/package.json
+++ b/package.json
@@ -11,14 +11,14 @@
     "test": "nyc mocha --timeout 30000 test/unit/",
     "test:integration": "bash test/integration/test-bchn-integration.sh",
     "test:integration:bchn": "bash test/integration/test-bchn-integration.sh",
-    "test:integration:abc": "RESTURL=https://abc.fullstack.cash/v3/ IS_USING_FREE_TIER=true mocha --timeout 30000 test/integration/",
+    "test:integration:abc": "RESTURL=https://abc.fullstack.cash/v4/ IS_USING_FREE_TIER=true mocha --timeout 30000 test/integration/",
     "test:integration:testnet": "IS_USING_FREE_TIER=true mocha --timeout 30000 test/integration/testnet/",
-    "test:integration:local": "RESTURL=http://localhost:3000/v3/ mocha --timeout 30000 test/integration",
-    "test:integration:local:bchn": "RESTURL=http://localhost:3000/v3/ bash test/integration/test-bchn-integration.sh",
-    "test:integration:local:testnet": "RESTURL=http://localhost:4000/v3/ mocha --timeout 30000 test/integration/testnet",
-    "test:temp": "RESTURL=http://bchn.fullstack.cash/v3/ mocha --timeout 30000 -g '#validateTxid' test/integration/bchn/",
-    "test:temp2": "RESTURL=http://abc.fullstack.cash/v3/ mocha --timeout 30000 -g '#validateTxid' test/integration/",
-    "test:integration:api": "RESTURL=https://api.fullstack.cash/v3/ mocha --timeout 30000 test/integration",
+    "test:integration:local": "RESTURL=http://localhost:3000/v4/ mocha --timeout 30000 test/integration",
+    "test:integration:local:bchn": "RESTURL=http://localhost:3000/v4/ bash test/integration/test-bchn-integration.sh",
+    "test:integration:local:testnet": "RESTURL=http://localhost:4000/v4/ mocha --timeout 30000 test/integration/testnet",
+    "test:temp": "RESTURL=http://bchn.fullstack.cash/v4/ mocha --timeout 30000 -g '#validateTxid' test/integration/bchn/",
+    "test:temp2": "RESTURL=http://abc.fullstack.cash/v4/ mocha --timeout 30000 -g '#validateTxid' test/integration/",
+    "test:integration:api": "RESTURL=https://api.fullstack.cash/v4/ mocha --timeout 30000 test/integration",
     "coverage": "nyc report --reporter=text-lcov | coveralls",
     "coverage:report": "nyc --reporter=html mocha --timeout 25000 test/unit/",
     "docs": "./node_modules/.bin/apidoc -i src/ -o docs"
diff --git a/src/address.js b/src/address.js
index 841a9ee..7b52ed8 100644
--- a/src/address.js
+++ b/src/address.js
@@ -6,7 +6,7 @@ const coininfo = require("coininfo")
 class Address {
   constructor(config) {
     const tmp = {}
-    if (!config || !config.restURL) tmp.restURL = `https://api.bchjs.cash/v3/`
+    if (!config || !config.restURL) tmp.restURL = `https://api.bchjs.cash/v4/`
     else tmp.restURL = config.restURL
 
     this.restURL = tmp.restURL
diff --git a/src/bch-js.js b/src/bch-js.js
index 8777ba5..175fd66 100644
--- a/src/bch-js.js
+++ b/src/bch-js.js
@@ -7,8 +7,7 @@
 */
 
 // bch-api mainnet.
-// const DEFAULT_REST_API = "https://api.bchjs.cash/v3/"
-const DEFAULT_REST_API = "https://api.fullstack.cash/v3/"
+const DEFAULT_REST_API = "https://api.fullstack.cash/v4/"
 
 // local deps
 const BitcoinCash = require("./bitcoincash")
diff --git a/test/e2e/rate-limits/anonymous-rate-limits.js b/test/e2e/rate-limits/anonymous-rate-limits.js
index 462dd98..4c2585c 100644
--- a/test/e2e/rate-limits/anonymous-rate-limits.js
+++ b/test/e2e/rate-limits/anonymous-rate-limits.js
@@ -14,9 +14,9 @@
 
 const assert = require("chai").assert
 
-// const RESTURL = `https://abc.fullstack.cash/v3/`
-const RESTURL = `https://bchn.fullstack.cash/v3/`
-// const RESTURL = `http://localhost:3000/v3/`
+// const RESTURL = `https://abc.fullstack.cash/v4/`
+const RESTURL = `https://bchn.fullstack.cash/v4/`
+// const RESTURL = `http://localhost:3000/v4/`
 
 const BCHJS = require("../../../src/bch-js")
 const bchjs = new BCHJS({ restURL: RESTURL })
diff --git a/test/e2e/rate-limits/basic-auth-rate-limits.js b/test/e2e/rate-limits/basic-auth-rate-limits.js
index c311e11..958d1a8 100644
--- a/test/e2e/rate-limits/basic-auth-rate-limits.js
+++ b/test/e2e/rate-limits/basic-auth-rate-limits.js
@@ -13,9 +13,9 @@ const PRO_PASS = "testpassword"
 
 const BCHJS = require("../../../src/bch-js")
 const bchjs = new BCHJS({
-  // restURL: `https://bchn.fullstack.cash/v3/`,
-  restURL: `https://abc.fullstack.cash/v3/`,
-  // restURL: `http://localhost:3000/v3/`,
+  // restURL: `https://bchn.fullstack.cash/v4/`,
+  restURL: `https://abc.fullstack.cash/v4/`,
+  // restURL: `http://localhost:3000/v4/`,
   authPass: PRO_PASS
 })
 
diff --git a/test/e2e/rate-limits/free-rate-limits.js b/test/e2e/rate-limits/free-rate-limits.js
index 736b9a8..e540be5 100644
--- a/test/e2e/rate-limits/free-rate-limits.js
+++ b/test/e2e/rate-limits/free-rate-limits.js
@@ -18,8 +18,8 @@ const JWT_TOKEN =
 
 const BCHJS = require("../../../src/bch-js")
 const bchjs = new BCHJS({
-  restURL: `https://api.fullstack.cash/v3/`,
-  // restURL: `http://localhost:3000/v3/`,
+  restURL: `https://api.fullstack.cash/v4/`,
+  // restURL: `http://localhost:3000/v4/`,
   apiToken: JWT_TOKEN
 })
 
diff --git a/test/e2e/rate-limits/full-node-rate-limits.js b/test/e2e/rate-limits/full-node-rate-limits.js
index 98b69fa..51d142a 100644
--- a/test/e2e/rate-limits/full-node-rate-limits.js
+++ b/test/e2e/rate-limits/full-node-rate-limits.js
@@ -18,9 +18,9 @@ const JWT_TOKEN =
 
 const BCHJS = require("../../../src/bch-js")
 const bchjs = new BCHJS({
-  // restURL: `https://bchn.fullstack.cash/v3/`,
-  restURL: `https:/abc.fullstack.cash/v3/`,
-  // restURL: `http://localhost:3000/v3/`,
+  // restURL: `https://bchn.fullstack.cash/v4/`,
+  restURL: `https:/abc.fullstack.cash/v4/`,
+  // restURL: `http://localhost:3000/v4/`,
   apiToken: JWT_TOKEN
 })
 
diff --git a/test/e2e/rate-limits/indexer-rate-limits.js b/test/e2e/rate-limits/indexer-rate-limits.js
index 7bee43e..a17ee9e 100644
--- a/test/e2e/rate-limits/indexer-rate-limits.js
+++ b/test/e2e/rate-limits/indexer-rate-limits.js
@@ -14,9 +14,9 @@ const JWT_TOKEN =
 
 const BCHJS = require("../../../src/bch-js")
 const bchjs = new BCHJS({
-  // restURL: `https://bchn.fullstack.cash/v3/`,
-  restURL: `https://abc.fullstack.cash/v3/`,
-  // restURL: `http://localhost:3000/v3/`,
+  // restURL: `https://bchn.fullstack.cash/v4/`,
+  restURL: `https://abc.fullstack.cash/v4/`,
+  // restURL: `http://localhost:3000/v4/`,
   apiToken: JWT_TOKEN
 })
 
diff --git a/test/integration/test-bchn-integration.sh b/test/integration/test-bchn-integration.sh
index edff741..fcc7811 100755
--- a/test/integration/test-bchn-integration.sh
+++ b/test/integration/test-bchn-integration.sh
@@ -1,7 +1,7 @@
 #!/bin/bash
 
-# export RESTURL=https://bchn.fullstack.cash/v3/
-#export RESTURL=http://localhost:3000/v3/
+# export RESTURL=https://bchn.fullstack.cash/v4/
+#export RESTURL=http://localhost:3000/v4/
 #export IS_USING_FREE_TIER=true
 
 cd test/integration/bchn/
diff --git a/test/integration/testnet/blockbook.js b/test/integration/testnet/blockbook.js
index d278d5d..5f653c9 100644
--- a/test/integration/testnet/blockbook.js
+++ b/test/integration/testnet/blockbook.js
@@ -8,11 +8,11 @@ const assert = chai.assert
 
 const RESTURL = process.env.RESTURL
   ? process.env.RESTURL
-  : `https://testnet3.fullstack.cash/v3/`
+  : `https://testnet3.fullstack.cash/v4/`
 // if (process.env.RESTURL) RESTURL = process.env.RESTURL
 
 const BCHJS = require("../../../src/bch-js")
-// const bchjs = new BCHJS({ restURL: `https://testnet.bchjs.cash/v3/` })
+// const bchjs = new BCHJS({ restURL: `https://testnet.bchjs.cash/v4/` })
 const bchjs = new BCHJS({ restURL: RESTURL, apiToken: process.env.BCHJSTOKEN })
 // const bchjs = new BCHJS({ restURL: RESTURL })
 //const axios = require("axios")
diff --git a/test/integration/testnet/blockchain.js b/test/integration/testnet/blockchain.js
index 859c3ac..41b2d46 100644
--- a/test/integration/testnet/blockchain.js
+++ b/test/integration/testnet/blockchain.js
@@ -12,11 +12,11 @@ const assert = chai.assert
 
 const RESTURL = process.env.RESTURL
   ? process.env.RESTURL
-  : "https://testnet3.fullstack.cash/v3/"
+  : "https://testnet3.fullstack.cash/v4/"
 // if (process.env.RESTURL) RESTURL = process.env.RESTURL
 
 const BCHJS = require("../../../src/bch-js")
-// const bchjs = new BCHJS({ restURL: `https://testnet.bchjs.cash/v3/` })
+// const bchjs = new BCHJS({ restURL: `https://testnet.bchjs.cash/v4/` })
 const bchjs = new BCHJS({ restURL: RESTURL, apiToken: process.env.BCHJSTOKEN })
 
 // Inspect utility used for debugging.
diff --git a/test/integration/testnet/control.js b/test/integration/testnet/control.js
index 102e0b0..028fb68 100644
--- a/test/integration/testnet/control.js
+++ b/test/integration/testnet/control.js
@@ -7,7 +7,7 @@ const assert = chai.assert
 
 const RESTURL = process.env.RESTURL
   ? process.env.RESTURL
-  : `https://testnet3.fullstack.cash/v3/`
+  : `https://testnet3.fullstack.cash/v4/`
 
 const BCHJS = require("../../../src/bch-js")
 const bchjs = new BCHJS({ restURL: RESTURL, apiToken: process.env.BCHJSTOKEN })
diff --git a/test/integration/testnet/electrumx.js b/test/integration/testnet/electrumx.js
index f4898c0..3e914ff 100644
--- a/test/integration/testnet/electrumx.js
+++ b/test/integration/testnet/electrumx.js
@@ -4,7 +4,7 @@ const sinon = require("sinon")
 
 const RESTURL = process.env.RESTURL
   ? process.env.RESTURL
-  : `https://testnet3.fullstack.cash/v3/`
+  : `https://testnet3.fullstack.cash/v4/`
 
 const BCHJS = require("../../../src/bch-js")
 const bchjs = new BCHJS({ restURL: RESTURL, apiToken: process.env.BCHJSTOKEN })
diff --git a/test/integration/testnet/rawtransaction.js b/test/integration/testnet/rawtransaction.js
index a79d009..4da6767 100644
--- a/test/integration/testnet/rawtransaction.js
+++ b/test/integration/testnet/rawtransaction.js
@@ -10,11 +10,11 @@ const assert = chai.assert
 
 const RESTURL = process.env.RESTURL
   ? process.env.RESTURL
-  : `https://testnet3.fullstack.cash/v3/`
+  : `https://testnet3.fullstack.cash/v4/`
 // if (process.env.RESTURL) RESTURL = process.env.RESTURL
 
 const BCHJS = require("../../../src/bch-js")
-// const bchjs = new BCHJS({ restURL: `https://testnet.bchjs.cash/v3/` })
+// const bchjs = new BCHJS({ restURL: `https://testnet.bchjs.cash/v4/` })
 const bchjs = new BCHJS({ restURL: RESTURL, apiToken: process.env.BCHJSTOKEN })
 
 // Inspect utility used for debugging.
diff --git a/test/integration/testnet/slp.js b/test/integration/testnet/slp.js
index d3d6c57..41c4b7f 100644
--- a/test/integration/testnet/slp.js
+++ b/test/integration/testnet/slp.js
@@ -7,11 +7,11 @@ const assert = chai.assert
 
 const RESTURL = process.env.RESTURL
   ? process.env.RESTURL
-  : `https://testnet3.fullstack.cash/v3/`
+  : `https://testnet3.fullstack.cash/v4/`
 // if (process.env.RESTURL) RESTURL = process.env.RESTURL
 
 const BCHJS = require("../../../src/bch-js")
-// const bchjs = new BCHJS({ restURL: `https://testnet.bchjs.cash/v3/` })
+// const bchjs = new BCHJS({ restURL: `https://testnet.bchjs.cash/v4/` })
 const bchjs = new BCHJS({ restURL: RESTURL, apiToken: process.env.BCHJSTOKEN })
 
 // Inspect utility used for debugging.
diff --git a/test/integration/testnet/test-free-tier.sh b/test/integration/testnet/test-free-tier.sh
index dd12f28..1558ce2 100755
--- a/test/integration/testnet/test-free-tier.sh
+++ b/test/integration/testnet/test-free-tier.sh
@@ -1,6 +1,6 @@
 #!/bin/bash
 
-export RESTURL=https://free-test.fullstack.cash/v3/
+export RESTURL=https://free-test.fullstack.cash/v4/
 export NETWORK=testnet
 export IS_USING_FREE_TIER=true
 
diff --git a/test/integration/testnet/util.js b/test/integration/testnet/util.js
index 0a5c2e7..7a77d37 100644
--- a/test/integration/testnet/util.js
+++ b/test/integration/testnet/util.js
@@ -8,11 +8,11 @@ const assert = chai.assert
 
 const RESTURL = process.env.RESTURL
   ? process.env.RESTURL
-  : `https://testnet3.fullstack.cash/v3/`
+  : `https://testnet3.fullstack.cash/v4/`
 // if (process.env.RESTURL) RESTURL = process.env.RESTURL
 
 const BCHJS = require("../../../src/bch-js")
-// const bchjs = new BCHJS({ restURL: `https://testnet.bchjs.cash/v3/` })
+// const bchjs = new BCHJS({ restURL: `https://testnet.bchjs.cash/v4/` })
 const bchjs = new BCHJS({ restURL: RESTURL, apiToken: process.env.BCHJSTOKEN })
 
 // Inspect utility used for debugging.
diff --git a/test/unit/slp-utils.js b/test/unit/slp-utils.js
index 47b88cc..70223ca 100644
--- a/test/unit/slp-utils.js
+++ b/test/unit/slp-utils.js
@@ -2,10 +2,10 @@ const assert = require("assert")
 const assert2 = require("chai").assert
 
 const SLP = require("../../src/slp/slp")
-//const slp = new SLP("http://decatur.hopto.org:12400/v3/")
+//const slp = new SLP("http://decatur.hopto.org:12400/v4/")
 //const slp = new SLP("https://rest.bitcoin.com/v2/")
 const slp = new SLP({
-  restURL: "https://api.fullstack.cash/v3/",
+  restURL: "https://api.fullstack.cash/v4/",
   apiToken: process.env.BCHJSTOKEN
 })
 
@@ -1979,7 +1979,7 @@ describe("#SLP Utils", () => {
         "3a4b628cbcc183ab376d44ce5252325f042268307ffa4a53443e92b6d24fb488"
       ]
 
-      const result = await bchjs.SLP.Utils.validateTxid(txids)
+      const result = await slp.Utils.validateTxid(txids)
       console.log(`result: ${JSON.stringify(result, null, 2)}`)
     })
   })