diff --git a/__tests__/lib/checkFile.test.ts b/__tests__/lib/checkFile.test.ts
deleted file mode 100644
index 3188af19f..000000000
--- a/__tests__/lib/checkFile.test.ts
+++ /dev/null
@@ -1,33 +0,0 @@
-import fs from 'fs';
-
-import { checkFilePath } from '../../src/lib/checkFile';
-
-describe('#checkFilePath', () => {
-  afterEach(() => {
-    jest.clearAllMocks();
-  });
-
-  it('should return error for empty path value', () => {
-    return expect(checkFilePath('')).toBe('An output path must be supplied.');
-  });
-
-  it('should return error if path already exists', () => {
-    expect.assertions(2);
-    const testPath = 'path-that-already-exists';
-
-    fs.existsSync = jest.fn(() => true);
-
-    expect(checkFilePath(testPath)).toBe('Specified output path already exists.');
-    expect(fs.existsSync).toHaveBeenCalledWith(testPath);
-  });
-
-  it("should return true if the path doesn't exist", () => {
-    expect.assertions(2);
-    const testPath = 'path-that-does-not-exist';
-
-    fs.existsSync = jest.fn(() => false);
-
-    expect(checkFilePath(testPath)).toBe(true);
-    expect(fs.existsSync).toHaveBeenCalledWith(testPath);
-  });
-});
diff --git a/__tests__/lib/validatePromptInput.test.ts b/__tests__/lib/validatePromptInput.test.ts
new file mode 100644
index 000000000..30c7ce2d5
--- /dev/null
+++ b/__tests__/lib/validatePromptInput.test.ts
@@ -0,0 +1,55 @@
+import fs from 'fs';
+
+import { validateFilePath, validateSubdomain } from '../../src/lib/validatePromptInput';
+
+describe('#validateFilePath', () => {
+  afterEach(() => {
+    jest.clearAllMocks();
+  });
+
+  it('should return error for empty path value', () => {
+    return expect(validateFilePath('')).toBe('An output path must be supplied.');
+  });
+
+  it('should return error if path already exists', () => {
+    expect.assertions(2);
+    const testPath = 'path-that-already-exists';
+
+    fs.existsSync = jest.fn(() => true);
+
+    expect(validateFilePath(testPath)).toBe('Specified output path already exists.');
+    expect(fs.existsSync).toHaveBeenCalledWith(testPath);
+  });
+
+  it("should return true if the path doesn't exist", () => {
+    expect.assertions(2);
+    const testPath = 'path-that-does-not-exist';
+
+    fs.existsSync = jest.fn(() => false);
+
+    expect(validateFilePath(testPath)).toBe(true);
+    expect(fs.existsSync).toHaveBeenCalledWith(testPath);
+  });
+});
+
+describe('#validateSubdomain', () => {
+  it('should validate basic subdomain', () => {
+    expect(validateSubdomain('subdomain')).toBe(true);
+  });
+
+  it('should validate subdomain with other characters', () => {
+    expect(validateSubdomain('test-Subdomain123')).toBe(true);
+  });
+
+  it('should reject subdomain with spaces', () => {
+    expect(validateSubdomain('test subdomain')).toBe(
+      'Project subdomain must contain only letters, numbers and dashes.'
+    );
+  });
+
+  it('should reject subdomain with special characters', () => {
+    expect(validateSubdomain('test-subdomain!')).toBe(
+      'Project subdomain must contain only letters, numbers and dashes.'
+    );
+  });
+});
diff --git a/src/cmds/openapi/convert.ts b/src/cmds/openapi/convert.ts
index c1d4ba14d..011dda2b6 100644
--- a/src/cmds/openapi/convert.ts
+++ b/src/cmds/openapi/convert.ts
@@ -8,9 +8,9 @@ import chalk from 'chalk';
 import prompts from 'prompts';
 
 import Command, { CommandCategories } from '../../lib/baseCommand';
-import { checkFilePath } from '../../lib/checkFile';
 import prepareOas from '../../lib/prepareOas';
 import promptTerminal from '../../lib/promptWrapper';
+import { validateFilePath } from '../../lib/validatePromptInput';
 
 export interface Options {
   spec?: string;
@@ -72,7 +72,7 @@ export default class OpenAPIConvertCommand extends Command {
           const extension = path.extname(specPath);
           return `${path.basename(specPath).split(extension)[0]}.openapi${extension}`;
         },
-        validate: value => checkFilePath(value),
+        validate: value => validateFilePath(value),
       },
     ]);
 
diff --git a/src/cmds/openapi/reduce.ts b/src/cmds/openapi/reduce.ts
index c53f1e6fe..7e18dbbc3 100644
--- a/src/cmds/openapi/reduce.ts
+++ b/src/cmds/openapi/reduce.ts
@@ -11,10 +11,10 @@ import ora from 'ora';
 import prompts from 'prompts';
 
 import Command, { CommandCategories } from '../../lib/baseCommand';
-import { checkFilePath } from '../../lib/checkFile';
 import { oraOptions } from '../../lib/logger';
 import prepareOas from '../../lib/prepareOas';
 import promptTerminal from '../../lib/promptWrapper';
+import { validateFilePath } from '../../lib/validatePromptInput';
 
 export interface Options {
   spec?: string;
@@ -170,7 +170,7 @@ export default class OpenAPIReduceCommand extends Command {
           const extension = path.extname(specPath);
           return `${path.basename(specPath).split(extension)[0]}.reduced${extension}`;
         },
-        validate: value => checkFilePath(value),
+        validate: value => validateFilePath(value),
       },
     ]);
 
diff --git a/src/lib/createGHA/index.ts b/src/lib/createGHA/index.ts
index e9472eaa8..2f7a3c01c 100644
--- a/src/lib/createGHA/index.ts
+++ b/src/lib/createGHA/index.ts
@@ -9,12 +9,12 @@ import chalk from 'chalk';
 import prompts from 'prompts';
 import simpleGit from 'simple-git';
 
-import { checkFilePath, cleanFileName } from '../checkFile';
 import configstore from '../configstore';
 import { getMajorPkgVersion } from '../getPkgVersion';
 import isCI, { isNpmScript, isTest } from '../isCI';
 import { debug, info } from '../logger';
 import promptTerminal from '../promptWrapper';
+import { cleanFileName, validateFilePath } from '../validatePromptInput';
 
 import yamlBase from './baseFile';
 
@@ -234,7 +234,7 @@ export default async function createGHA(
           type: 'text',
           initial: cleanFileName(`rdme-${command}`),
           format: prev => getGHAFileName(prev),
-          validate: value => checkFilePath(value, getGHAFileName),
+          validate: value => validateFilePath(value, getGHAFileName),
         },
       ],
       {
diff --git a/src/lib/loginFlow.ts b/src/lib/loginFlow.ts
index 3626e3003..d4e7b7511 100644
--- a/src/lib/loginFlow.ts
+++ b/src/lib/loginFlow.ts
@@ -7,6 +7,7 @@ import fetch, { handleRes } from './fetch';
 import getCurrentConfig from './getCurrentConfig';
 import { debug } from './logger';
 import promptTerminal from './promptWrapper';
+import { validateSubdomain } from './validatePromptInput';
 
 interface LoginBody {
   email?: string;
@@ -51,8 +52,9 @@ export default async function loginFlow(otp?: string) {
     {
       type: 'text',
       name: 'project',
-      message: 'What project are you logging into?',
+      message: 'What project subdomain are you logging into?',
       initial: storedConfig.project,
+      validate: validateSubdomain,
     },
   ]);
 
diff --git a/src/lib/checkFile.ts b/src/lib/validatePromptInput.ts
similarity index 61%
rename from src/lib/checkFile.ts
rename to src/lib/validatePromptInput.ts
index aec4e5f73..9f32f20e6 100644
--- a/src/lib/checkFile.ts
+++ b/src/lib/validatePromptInput.ts
@@ -16,7 +16,7 @@ export const cleanFileName = (input: string) => input.replace(/[^a-z0-9]/gi, '-'
  * @returns true if path is valid (i.e. is non-empty and doesn't already exist),
  * otherwise a string containing the error message
  */
-export function checkFilePath(value: string, getFullPath: (file: string) => string = file => file) {
+export function validateFilePath(value: string, getFullPath: (file: string) => string = file => file) {
   if (value.length) {
     const fullPath = getFullPath(value);
     if (!fs.existsSync(fullPath)) {
@@ -28,3 +28,16 @@ export function checkFilePath(value: string, getFullPath: (file: string) => stri
 
   return 'An output path must be supplied.';
 }
+
+/**
+ * Validates that a project subdomain value is valid.
+ *
+ * @param value the terminal input
+ * @returns true if the subdomain value is valid, else an error message
+ */
+export function validateSubdomain(value: string) {
+  return (
+    // eslint-disable-next-line unicorn/no-unsafe-regex
+    /^[a-zA-Z0-9]+(-[a-zA-Z0-9]+)*$/.test(value) || 'Project subdomain must contain only letters, numbers and dashes.'
+  );
+}