diff --git a/package-lock.json b/package-lock.json
index 2a9796fb..14aa4f61 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -43,7 +43,8 @@
         "react-toastify": "^10.0.6",
         "tailwind-merge": "^2.4.0",
         "tailwindcss-animate": "^1.0.7",
-        "vaul": "^0.9.1"
+        "vaul": "^0.9.1",
+        "zod": "^3.24.1"
       },
       "devDependencies": {
         "@playwright/test": "^1.47.2",
@@ -7419,6 +7420,15 @@
       "funding": {
         "url": "https://github.com/sponsors/sindresorhus"
       }
+    },
+    "node_modules/zod": {
+      "version": "3.24.1",
+      "resolved": "https://registry.npmjs.org/zod/-/zod-3.24.1.tgz",
+      "integrity": "sha512-muH7gBL9sI1nciMZV67X5fTKKBLtwpZ5VBp1vsOQzj1MhrBZ4wlVCm3gedKZWLp0Oyel8sIGfeiz54Su+OVT+A==",
+      "license": "MIT",
+      "funding": {
+        "url": "https://github.com/sponsors/colinhacks"
+      }
     }
   }
 }
diff --git a/package.json b/package.json
index e6ef7213..c854b6a6 100644
--- a/package.json
+++ b/package.json
@@ -48,7 +48,8 @@
     "react-toastify": "^10.0.6",
     "tailwind-merge": "^2.4.0",
     "tailwindcss-animate": "^1.0.7",
-    "vaul": "^0.9.1"
+    "vaul": "^0.9.1",
+    "zod": "^3.24.1"
   },
   "devDependencies": {
     "@playwright/test": "^1.47.2",
diff --git a/src/components/ProgramLoader/BinaryFileUpload.tsx b/src/components/ProgramLoader/BinaryFileUpload.tsx
deleted file mode 100644
index be9cf390..00000000
--- a/src/components/ProgramLoader/BinaryFileUpload.tsx
+++ /dev/null
@@ -1,63 +0,0 @@
-import { Input } from "../ui/input";
-import { ProgramUploadFileOutput } from "./types";
-import { decodeStandardProgram } from "@typeberry/pvm-debugger-adapter";
-import { RegistersArray } from "@/types/pvm.ts";
-
-export const BinaryFileUpload = ({
-  onFileUpload,
-  close,
-}: {
-  onFileUpload: (val: ProgramUploadFileOutput) => void;
-  close?: () => void;
-}) => {
-  let fileReader: FileReader;
-
-  const handleFileRead = (e: ProgressEvent<FileReader>) => {
-    const arrayBuffer = e.target?.result;
-
-    if (arrayBuffer instanceof ArrayBuffer) {
-      const uint8Array = new Uint8Array(arrayBuffer);
-      const { code, /*memory,*/ registers } = decodeStandardProgram(uint8Array, new Uint8Array());
-
-      onFileUpload({
-        program: Array.from(code),
-        name: "custom",
-        initial: {
-          regs: Array.from(registers) as RegistersArray,
-          pc: 0,
-          pageMap: [],
-          // TODO: map memory properly
-          // memory: [...memory],
-          gas: 10000n,
-        },
-      });
-    } else {
-      console.error("Unexpected result type:", arrayBuffer);
-    }
-  };
-
-  const handleProgramUpload = (file: Blob) => {
-    fileReader = new FileReader();
-    fileReader.onload = handleFileRead;
-    fileReader.readAsArrayBuffer(file);
-  };
-
-  return (
-    <div className="block">
-      <p className="mb-3">Upload program as a binary file</p>
-      <Input
-        className="my-6 mr-3"
-        id="test-file"
-        type="file"
-        accept=".bin,.pvm"
-        onClick={(e) => e.stopPropagation()}
-        onChange={(e) => {
-          if (e.target.files?.length) {
-            handleProgramUpload(e.target.files[0]);
-            close?.();
-          }
-        }}
-      />
-    </div>
-  );
-};
diff --git a/src/components/ProgramLoader/Bytecode.tsx b/src/components/ProgramLoader/Bytecode.tsx
deleted file mode 100644
index c087dd9e..00000000
--- a/src/components/ProgramLoader/Bytecode.tsx
+++ /dev/null
@@ -1,18 +0,0 @@
-import { ProgramUploadFileOutput } from "./types";
-import { BinaryFileUpload } from "@/components/ProgramLoader/BinaryFileUpload.tsx";
-
-export const Bytecode = ({
-  onProgramLoad,
-}: {
-  onProgramLoad: (val?: ProgramUploadFileOutput, error?: string) => void;
-}) => {
-  const handleFileUpload = (val: ProgramUploadFileOutput) => {
-    onProgramLoad(val);
-  };
-
-  return (
-    <div className="h-full flex flex-col">
-      <BinaryFileUpload onFileUpload={handleFileUpload} />
-    </div>
-  );
-};
diff --git a/src/components/ProgramLoader/Examples.tsx b/src/components/ProgramLoader/Examples.tsx
index 94f416ed..ad7eb111 100644
--- a/src/components/ProgramLoader/Examples.tsx
+++ b/src/components/ProgramLoader/Examples.tsx
@@ -106,7 +106,7 @@ const programs: {
 export const Examples = ({ onProgramLoad }: { onProgramLoad: (val: ProgramUploadFileOutput) => void }) => {
   return (
     <div>
-      <p className="mb-2">Load example test file</p>
+      <h2 className="text-lg mb-4">Load an example test file</h2>
       <RadioGroup
         defaultValue="option-fibonacci"
         onValueChange={(val) =>
diff --git a/src/components/ProgramLoader/Loader.tsx b/src/components/ProgramLoader/Loader.tsx
index 097335c1..9b076306 100644
--- a/src/components/ProgramLoader/Loader.tsx
+++ b/src/components/ProgramLoader/Loader.tsx
@@ -1,8 +1,6 @@
 import { Tabs, TabsList, TabsTrigger, TabsContent } from "@/components/ui/tabs";
 import { Button } from "../ui/button";
-import { Bytecode } from "./Bytecode";
 import { Examples } from "./Examples";
-import { TextFileUpload } from "./TextFileUpload";
 import { useState, useCallback, useEffect } from "react";
 import { ProgramUploadFileOutput } from "./types";
 import { useDebuggerActions } from "@/hooks/useDebuggerActions";
@@ -10,6 +8,7 @@ import { useAppDispatch, useAppSelector } from "@/store/hooks.ts";
 import { setIsProgramEditMode } from "@/store/debugger/debuggerSlice.ts";
 import { selectIsAnyWorkerLoading } from "@/store/workers/workersSlice";
 import { isSerializedError } from "@/store/utils";
+import { ProgramFileUpload } from "@/components/ProgramLoader/ProgramFileUpload.tsx";
 
 export const Loader = ({ setIsDialogOpen }: { setIsDialogOpen?: (val: boolean) => void }) => {
   const dispatch = useAppDispatch();
@@ -44,17 +43,19 @@ export const Loader = ({ setIsDialogOpen }: { setIsDialogOpen?: (val: boolean) =
     <>
       <Tabs className="flex-1 flex flex-col items-start overflow-auto" defaultValue="upload">
         <TabsList>
-          <TabsTrigger value="upload">JSON tests</TabsTrigger>
-          <TabsTrigger value="examples">Examples</TabsTrigger>
-          <TabsTrigger value="bytecode">RAW bytecode</TabsTrigger>
+          <TabsTrigger value="upload">Upload file</TabsTrigger>
+          <TabsTrigger value="examples">Start with examples</TabsTrigger>
         </TabsList>
         <div className="border-2 rounded p-4 flex-1 flex flex-col w-full h-full overflow-auto md:px-5">
           <TabsContent value="upload">
-            <TextFileUpload
+            <ProgramFileUpload
               onFileUpload={(val) => {
                 setProgramLoad(val);
                 setIsSubmitted(false);
               }}
+              onParseError={(error) => {
+                setError(error);
+              }}
             />
           </TabsContent>
           <TabsContent value="examples">
@@ -65,16 +66,7 @@ export const Loader = ({ setIsDialogOpen }: { setIsDialogOpen?: (val: boolean) =
               }}
             />
           </TabsContent>
-          <TabsContent value="bytecode">
-            <Bytecode
-              onProgramLoad={(val, error) => {
-                setProgramLoad(val);
-                setIsSubmitted(false);
-                setError(error);
-              }}
-            />
-          </TabsContent>
-          {error && isSubmitted && <p className="text-red-500">{error}</p>}
+          {error && isSubmitted && <p className="text-red-500 whitespace-pre-line">{error}</p>}
         </div>
       </Tabs>
       <Button className="mt-3" id="load-button" type="button" onClick={handleLoad}>
diff --git a/src/components/ProgramLoader/ProgramFileUpload.tsx b/src/components/ProgramLoader/ProgramFileUpload.tsx
new file mode 100644
index 00000000..e5565532
--- /dev/null
+++ b/src/components/ProgramLoader/ProgramFileUpload.tsx
@@ -0,0 +1,180 @@
+import { ExternalLink } from "lucide-react";
+import { Input } from "../ui/input";
+import { ProgramUploadFileOutput } from "./types";
+import { mapUploadFileInputToOutput } from "./utils";
+import { decodeStandardProgram } from "@typeberry/pvm-debugger-adapter";
+import { RegistersArray } from "@/types/pvm.ts";
+import { SafeParseReturnType, z } from "zod";
+
+const validateJsonTestCaseSchema = (json: unknown) => {
+  const pageMapSchema = z.object({
+    address: z.number(),
+    length: z.number(),
+    "is-writable": z.boolean(),
+  });
+
+  const memorySchema = z.object({
+    address: z.number(),
+    contents: z.array(z.number()),
+  });
+
+  const schema = z.object({
+    name: z.string(),
+    "initial-regs": z.array(z.number()).length(13),
+    "initial-pc": z.number(),
+    "initial-page-map": z.array(pageMapSchema),
+    "initial-memory": z.array(memorySchema),
+    "initial-gas": z.number(),
+    program: z.array(z.number()),
+    "expected-status": z.string(),
+    "expected-regs": z.array(z.number()),
+    "expected-pc": z.number(),
+    "expected-memory": z.array(memorySchema),
+    "expected-gas": z.number(),
+  });
+
+  return schema.safeParse(json);
+};
+
+const generateErrorMessageFromZodValidation = (result: SafeParseReturnType<unknown, unknown>) => {
+  if (!result.error) {
+    return false;
+  }
+
+  const formattedErrors = result.error.errors.map((err) => {
+    const path = err.path.join(" > ") || "root";
+    return `Field: "${path}" - ${err.message}`;
+  });
+
+  return `File validation failed with the following errors:\n\n${formattedErrors.join("\n")}`;
+};
+
+export const ProgramFileUpload = ({
+  onFileUpload,
+  onParseError,
+  close,
+}: {
+  onFileUpload: (val: ProgramUploadFileOutput) => void;
+  onParseError: (error: string) => void;
+  close?: () => void;
+}) => {
+  let fileReader: FileReader;
+
+  const handleFileRead = (e: ProgressEvent<FileReader>) => {
+    const arrayBuffer = e.target?.result;
+
+    if (arrayBuffer instanceof ArrayBuffer) {
+      // Try to parse file as a JSON first
+      try {
+        const stringContent = new TextDecoder("utf-8").decode(arrayBuffer);
+
+        const jsonFile = JSON.parse(stringContent);
+
+        const result = validateJsonTestCaseSchema(jsonFile);
+
+        if (!result.success) {
+          const errorMessage = generateErrorMessageFromZodValidation(result);
+          onParseError(errorMessage || "");
+        } else {
+          onFileUpload(mapUploadFileInputToOutput(jsonFile));
+        }
+      } catch (e) {
+        const uint8Array = new Uint8Array(arrayBuffer);
+
+        // Try to decode the program as an SPI
+        try {
+          const { code, /*memory,*/ registers } = decodeStandardProgram(uint8Array, new Uint8Array());
+
+          onFileUpload({
+            program: Array.from(code),
+            name: "custom",
+            initial: {
+              regs: Array.from(registers) as RegistersArray,
+              pc: 0,
+              pageMap: [],
+              // TODO: map memory properly
+              // memory: [...memory],
+              gas: 10000n,
+            },
+          });
+        } catch (e) {
+          // Try to load program as a Generic
+          onFileUpload({
+            program: Array.from(uint8Array),
+            name: "custom",
+            initial: {
+              regs: Array.from([0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]) as RegistersArray,
+              pc: 0,
+              pageMap: [],
+              gas: 10000n,
+            },
+          });
+        }
+      }
+    }
+  };
+
+  const handleProgramUpload = (file: Blob) => {
+    fileReader = new FileReader();
+    fileReader.onloadend = handleFileRead;
+    fileReader.readAsArrayBuffer(file);
+  };
+
+  return (
+    <div className="block pb-[100px]">
+      <h2 className="text-lg">Load a file in one of the following formats:</h2>
+      <ul className="list-disc p-4">
+        <li>
+          <p>JSON test file compatible with JAM TestVectors JSON</p>
+          <p>
+            <small>
+              Examples can be found in <a href="https://github.com/w3f/jamtestvectors">wf3/jamtestvectors</a> Github
+              repo&nbsp;
+              <a href="https://github.com/w3f/jamtestvectors/pull/3/files" target="_blank">
+                <ExternalLink className="inline w-4 mb-1 text-blue-600" />
+              </a>
+            </small>
+          </p>
+        </li>
+        <li>
+          <p>JAM SPI program</p>
+          <p>
+            <small>
+              SPI program definition can be found in
+              <a href="https://graypaper.fluffylabs.dev/#/5b732de/2a7e022a7e02" target="_blank">
+                &nbsp;a GrayPaper&nbsp;
+                <ExternalLink className="inline w-4 mb-1 text-blue-600" />
+              </a>
+            </small>
+          </p>
+        </li>
+        <li>
+          <p>Generic PVM program</p>
+          <p>
+            <small>
+              Generic program definition can be found in
+              <a href="https://graypaper.fluffylabs.dev/#/5b732de/23c60023c600" target="_blank">
+                &nbsp;a GrayPaper&nbsp;
+                <ExternalLink className="inline w-4 mb-1 text-blue-600" />
+              </a>
+            </small>
+          </p>
+        </li>
+      </ul>
+
+      <Input
+        className="mt-5 mr-3"
+        id="test-file"
+        type="file"
+        accept=".bin,.pvm,.json"
+        onClick={(e) => e.stopPropagation()}
+        onChange={(e) => {
+          if (e.target.files?.length) {
+            handleProgramUpload(e.target.files[0]);
+            close?.();
+          }
+        }}
+      />
+    </div>
+  );
+};
diff --git a/src/components/ProgramLoader/TextFileUpload.tsx b/src/components/ProgramLoader/TextFileUpload.tsx
deleted file mode 100644
index b07d5a68..00000000
--- a/src/components/ProgramLoader/TextFileUpload.tsx
+++ /dev/null
@@ -1,62 +0,0 @@
-import { ExternalLink } from "lucide-react";
-import { Input } from "../ui/input";
-import { ProgramUploadFileOutput } from "./types";
-import { mapUploadFileInputToOutput } from "./utils";
-
-export const TextFileUpload = ({
-  onFileUpload,
-  close,
-}: {
-  onFileUpload: (val: ProgramUploadFileOutput) => void;
-  close?: () => void;
-}) => {
-  let fileReader: FileReader;
-
-  const handleFileRead = () => {
-    const fileContent = fileReader?.result;
-
-    try {
-      if (fileContent !== null && typeof fileContent === "string") {
-        const jsonFile = JSON.parse(fileContent);
-        onFileUpload(mapUploadFileInputToOutput(jsonFile));
-      } else {
-        alert("Cannot read file");
-      }
-    } catch (e) {
-      alert("Cannot parse JSON");
-    }
-  };
-
-  const handleProgramUpload = (file: Blob) => {
-    fileReader = new FileReader();
-    fileReader.onloadend = handleFileRead;
-    fileReader.readAsText(file);
-  };
-
-  return (
-    <div className="block pb-[100px]">
-      <p>Load JSON testfile compatible with JAM TestVectors JSON</p>
-      <p>
-        <small>
-          Examples can be found in <a href="https://github.com/w3f/jamtestvectors">wf3/jamtestvectors</a> Github repo.
-          <a href="https://github.com/w3f/jamtestvectors/pull/3/files" target="_blank">
-            <ExternalLink className="inline w-4 mb-1 text-blue-600" />
-          </a>
-        </small>
-      </p>
-      <Input
-        className="mt-5 mr-3"
-        id="test-file"
-        type="file"
-        accept="application/json"
-        onClick={(e) => e.stopPropagation()}
-        onChange={(e) => {
-          if (e.target.files?.length) {
-            handleProgramUpload(e.target.files[0]);
-            close?.();
-          }
-        }}
-      />
-    </div>
-  );
-};