diff --git a/components/Tabs.tsx b/components/Tabs.tsx
index bfa74d4..1a351ea 100644
--- a/components/Tabs.tsx
+++ b/components/Tabs.tsx
@@ -1,24 +1,58 @@
-import { useEffect, useState } from "react";
+import React, { useEffect, useState, Fragment, isValidElement, useCallback } from "react";
 import type { ReactNode, ReactElement } from "react";
-import { Button, Stack } from ".";
+import { Box, Button, Flex, Input, Stack, Text } from ".";
+import {
+  Dialog,
+  DialogTrigger,
+  DialogContent,
+  DialogTitle,
+  DialogDescription,
+  DialogClose,
+} from "./Dialog";
+import { Plus, X } from "phosphor-react";
+import { styled } from "../stitches.config";
+
+const ErrorText = styled(Text, {
+  color: "$red9",
+  mt: "$1",
+  display: "block",
+});
 
 interface TabProps {
   header?: string;
   children: ReactNode;
 }
 
+// TODO customise strings shown
 interface Props {
   activeIndex?: number;
   activeHeader?: string;
   headless?: boolean;
   children: ReactElement<TabProps>[];
+  keepAllAlive?: boolean;
+  defaultExtension?: string;
+  onCreateNewTab?: (name: string) => any;
+  onCloseTab?: (index: number, header?: string) => any;
 }
 
 export const Tab = (props: TabProps) => null;
 
-export const Tabs = ({ children, activeIndex, activeHeader, headless }: Props) => {
+export const Tabs = ({
+  children,
+  activeIndex,
+  activeHeader,
+  headless,
+  keepAllAlive = false,
+  onCreateNewTab,
+  onCloseTab,
+  defaultExtension = "",
+}: Props) => {
   const [active, setActive] = useState(activeIndex || 0);
-  const tabProps: TabProps[] = children.map(elem => elem.props);
+  const tabs: TabProps[] = children.map(elem => elem.props);
+
+  const [isNewtabDialogOpen, setIsNewtabDialogOpen] = useState(false);
+  const [tabname, setTabname] = useState("");
+  const [newtabError, setNewtabError] = useState<string | null>(null);
 
   useEffect(() => {
     if (activeIndex) setActive(activeIndex);
@@ -26,10 +60,53 @@ export const Tabs = ({ children, activeIndex, activeHeader, headless }: Props) =
 
   useEffect(() => {
     if (activeHeader) {
-      const idx = tabProps.findIndex(tab => tab.header === activeHeader);
+      const idx = tabs.findIndex(tab => tab.header === activeHeader);
       setActive(idx);
     }
-  }, [activeHeader, tabProps]);
+  }, [activeHeader, tabs]);
+
+  // when filename changes, reset error
+  useEffect(() => {
+    setNewtabError(null);
+  }, [tabname, setNewtabError]);
+
+  const validateTabname = useCallback(
+    (tabname: string): { error: string | null } => {
+      if (tabs.find(tab => tab.header === tabname)) {
+        return { error: "Name already exists." };
+      }
+      return { error: null };
+    },
+    [tabs]
+  );
+
+  const handleCreateTab = useCallback(() => {
+    // add default extension in case omitted
+    let _tabname = tabname.includes(".") ? tabname : tabname + defaultExtension;
+    const chk = validateTabname(_tabname);
+    if (chk.error) {
+      setNewtabError(`Error: ${chk.error}`);
+      return;
+    }
+
+    setIsNewtabDialogOpen(false);
+    setTabname("");
+    // switch to new tab?
+    setActive(tabs.length);
+
+    onCreateNewTab?.(_tabname);
+  }, [tabname, defaultExtension, validateTabname, onCreateNewTab, tabs.length]);
+
+  const handleCloseTab = useCallback(
+    (idx: number) => {
+      if (idx <= active && active !== 0) {
+        setActive(active - 1);
+      }
+
+      onCloseTab?.(idx, tabs[idx].header);
+    },
+    [active, onCloseTab, tabs]
+  );
 
   return (
     <>
@@ -42,9 +119,9 @@ export const Tabs = ({ children, activeIndex, activeHeader, headless }: Props) =
             marginBottom: "-1px",
           }}
         >
-          {tabProps.map((prop, idx) => (
+          {tabs.map((tab, idx) => (
             <Button
-              key={prop.header}
+              key={tab.header}
               role="tab"
               tabIndex={idx}
               onClick={() => setActive(idx)}
@@ -59,12 +136,99 @@ export const Tabs = ({ children, activeIndex, activeHeader, headless }: Props) =
                 },
               }}
             >
-              {prop.header || idx}
+              {tab.header || idx}
+              {onCloseTab && (
+                <Box
+                  as="span"
+                  css={{
+                    display: "flex",
+                    p: "2px",
+                    borderRadius: "$full",
+                    mr: "-4px",
+                    "&:hover": {
+                      // boxSizing: "0px 0px 1px",
+                      backgroundColor: "$mauve2",
+                      color: "$mauve12",
+                    },
+                  }}
+                  onClick={(ev: React.MouseEvent<HTMLElement>) => {
+                    ev.stopPropagation();
+                    handleCloseTab(idx);
+                  }}
+                >
+                  <X size="9px" weight="bold" />
+                </Box>
+              )}
             </Button>
           ))}
+          {onCreateNewTab && (
+            <Dialog open={isNewtabDialogOpen} onOpenChange={setIsNewtabDialogOpen}>
+              <DialogTrigger asChild>
+                <Button ghost size="sm" css={{ alignItems: "center", px: "$2", mr: "$3" }}>
+                  <Plus size="16px" /> {tabs.length === 0 && "Add new tab"}
+                </Button>
+              </DialogTrigger>
+              <DialogContent>
+                <DialogTitle>Create new tab</DialogTitle>
+                <DialogDescription>
+                  <label>Tabname</label>
+                  <Input
+                    value={tabname}
+                    onChange={e => setTabname(e.target.value)}
+                    onKeyPress={e => {
+                      if (e.key === "Enter") {
+                        handleCreateTab();
+                      }
+                    }}
+                  />
+                  <ErrorText>{newtabError}</ErrorText>
+                </DialogDescription>
+
+                <Flex
+                  css={{
+                    marginTop: 25,
+                    justifyContent: "flex-end",
+                    gap: "$3",
+                  }}
+                >
+                  <DialogClose asChild>
+                    <Button outline>Cancel</Button>
+                  </DialogClose>
+                  <Button variant="primary" onClick={handleCreateTab}>
+                    Create
+                  </Button>
+                </Flex>
+                <DialogClose asChild>
+                  <Box css={{ position: "absolute", top: "$3", right: "$3" }}>
+                    <X size="20px" />
+                  </Box>
+                </DialogClose>
+              </DialogContent>
+            </Dialog>
+          )}
         </Stack>
       )}
-      {tabProps[active].children}
+      {keepAllAlive ? (
+        tabs.map((tab, idx) => {
+          // TODO Maybe rule out fragments as children
+          if (!isValidElement(tab.children)) {
+            if (active !== idx) return null;
+            return tab.children;
+          }
+          let key = tab.children.key || tab.header || idx;
+          let { children } = tab;
+          let { style, ...props } = children.props;
+          return (
+            <children.type
+              key={key}
+              {...props}
+              style={{ ...style, display: active !== idx ? "none" : undefined }}
+            />
+          );
+        })
+      ) : (
+        <Fragment key={tabs[active].header || active}>{tabs[active].children}</Fragment>
+      )}
     </>
   );
 };
diff --git a/pages/test/[[...slug]].tsx b/pages/test/[[...slug]].tsx
index 79416d8..dd122b7 100644
--- a/pages/test/[[...slug]].tsx
+++ b/pages/test/[[...slug]].tsx
@@ -4,7 +4,7 @@ import dynamic from "next/dynamic";
 import { useSnapshot } from "valtio";
 import state from "../../state";
 import { sendTransaction } from "../../state/actions";
-import { useCallback, useEffect, useState } from "react";
+import { useCallback, useEffect, useState, FC } from "react";
 import transactionsData from "../../content/transactions.json";
 
 const LogBox = dynamic(() => import("../../components/LogBox"), {
@@ -18,7 +18,7 @@ const Accounts = dynamic(() => import("../../components/Accounts"), {
 type TxFields = Omit<typeof transactionsData[0], "Account" | "Sequence" | "TransactionType">;
 type OtherFields = (keyof Omit<TxFields, "Destination">)[];
 
-const Transaction = () => {
+const Transaction: FC = props => {
   const snap = useSnapshot(state);
 
   const transactionsOptions = transactionsData.map(tx => ({
@@ -150,7 +150,7 @@ const Transaction = () => {
   const usualFields = ["TransactionType", "Amount", "Account", "Destination"];
   const otherFields = Object.keys(txFields).filter(k => !usualFields.includes(k)) as OtherFields;
   return (
-    <Box css={{ position: "relative", height: "calc(100% - 28px)" }}>
+    <Box css={{ position: "relative", height: "calc(100% - 28px)" }} {...props}>
       <Container css={{ p: "$3 0", fontSize: "$sm", height: "calc(100% - 28px)" }}>
         <Flex column fluid css={{ height: "100%", overflowY: "auto" }}>
           <Flex row fluid css={{ justifyContent: "flex-end", alignItems: "center", mb: "$3" }}>
@@ -280,6 +280,7 @@ const Transaction = () => {
 
 const Test = () => {
   const snap = useSnapshot(state);
+  const [tabHeaders, setTabHeaders] = useState<string[]>(["test1.json"]);
   return (
     <Container css={{ py: "$3", px: 0 }}>
       <Flex
@@ -288,14 +289,17 @@ const Test = () => {
         css={{ justifyContent: "center", mb: "$2", height: "40vh", minHeight: "300px", p: "$3 $2" }}
       >
         <Box css={{ width: "60%", px: "$2", maxWidth: "800px", height: "100%", overflow: "auto" }}>
-          <Tabs>
-            {/* TODO Dynamic tabs */}
-            <Tab header="test1.json">
-              <Transaction />
-            </Tab>
-            <Tab header="test2.json">
-              <Transaction />
-            </Tab>
+          <Tabs
+            keepAllAlive
+            defaultExtension=".json"
+            onCreateNewTab={name => setTabHeaders(tabHeaders.concat(name))}
+            onCloseTab={index => setTabHeaders(tabHeaders.filter((_, idx) => idx !== index))}
+          >
+            {tabHeaders.map(header => (
+              <Tab key={header} header={header}>
+                <Transaction />
+              </Tab>
+            ))}
           </Tabs>
         </Box>
         <Box css={{ width: "40%", mx: "$2", height: "100%", maxWidth: "750px" }}>