diff --git a/apps/studio/compat/next/api.test.ts b/apps/studio/compat/next/api.test.ts
new file mode 100644
index 00000000000..28f64efd36d
--- /dev/null
+++ b/apps/studio/compat/next/api.test.ts
@@ -0,0 +1,213 @@
+import type { NextApiRequest, NextApiResponse } from 'next'
+import { describe, expect, it, vi } from 'vitest'
+
+import { toWebHandler } from './api'
+
+const createRequest = (body?: string, contentType = 'application/json') =>
+  new Request('http://localhost/api/test', {
+    method: 'POST',
+    headers: { 'content-type': contentType },
+    body,
+  })
+
+describe('toWebHandler request parsing', () => {
+  it.each(
+    ['application/json', 'application/ld+json', 'Application/JSON; charset=utf-8'].flatMap(
+      (contentType) =>
+        ['{', '[1,', 'undefined', '   ', '{"private":"value",}'].map((body) => ({
+          contentType,
+          body,
+        }))
+    )
+  )(
+    'returns 400 without calling the handler for malformed $contentType: $body',
+    async ({ body, contentType }) => {
+      const handler = vi.fn()
+      const response = await toWebHandler(handler)({ request: createRequest(body, contentType) })
+
+      expect(response.status).toBe(400)
+      expect(await response.text()).toBe('Invalid JSON')
+      expect(handler).not.toHaveBeenCalled()
+    }
+  )
+
+  it.each<[string | undefined, unknown]>([
+    ['{"query":"select 1"}', { query: 'select 1' }],
+    ['[1,"two",null]', [1, 'two', null]],
+    ['"hello"', 'hello'],
+    ['42', 42],
+    ['true', true],
+    ['false', false],
+    ['null', null],
+    ['', {}],
+    [undefined, {}],
+  ])('passes valid JSON %s to the handler', async (body, expected) => {
+    const handler = vi.fn((req: NextApiRequest, res: NextApiResponse) => {
+      expect(req.body).toEqual(expected)
+      res.status(201).setHeader('x-handler', 'called')
+      res.json({ success: true })
+    })
+
+    const response = await toWebHandler(handler)({ request: createRequest(body) })
+
+    expect(handler).toHaveBeenCalledOnce()
+    expect(response.status).toBe(201)
+    expect(response.headers.get('x-handler')).toBe('called')
+    expect(response.headers.get('content-type')).toBe('application/json')
+    expect(await response.json()).toEqual({ success: true })
+  })
+
+  it.each(['application/json; charset=utf-8', 'application/ld+json', 'Application/JSON'])(
+    'accepts JSON content type %s',
+    async (contentType) => {
+      const handler = vi.fn((req: NextApiRequest, res: NextApiResponse) => res.json(req.body))
+      const response = await toWebHandler(handler)({
+        request: createRequest('{"name":"café"}', contentType),
+      })
+
+      expect(await response.json()).toEqual({ name: 'café' })
+    }
+  )
+
+  it.each<[string, string, unknown]>([
+    [
+      'name=hello+world&value=%26%3D',
+      'application/x-www-form-urlencoded',
+      {
+        name: 'hello world',
+        value: '&=',
+      },
+    ],
+    ['{', 'text/plain', '{'],
+    ['{', 'text/plain; note="application/json"', '{'],
+    ['{', 'application/jsonx', '{'],
+  ])('preserves non-JSON request bodies', async (body, contentType, expected) => {
+    const handler = vi.fn((req: NextApiRequest, res: NextApiResponse) => {
+      expect(req.body).toEqual(expected)
+      res.end('ok')
+    })
+
+    const response = await toWebHandler(handler)({ request: createRequest(body, contentType) })
+
+    expect(handler).toHaveBeenCalledOnce()
+    expect(await response.text()).toBe('ok')
+  })
+
+  it.each(['GET', 'HEAD'])('leaves %s bodies undefined', async (method) => {
+    const handler = vi.fn((req: NextApiRequest, res: NextApiResponse) => {
+      expect(req.method).toBe(method)
+      expect(req.body).toBeUndefined()
+      res.end()
+    })
+
+    await toWebHandler(handler)({
+      request: new Request('http://localhost/api/test', {
+        method,
+        headers: { 'content-type': 'application/json' },
+      }),
+    })
+
+    expect(handler).toHaveBeenCalledOnce()
+  })
+
+  it('preserves the URL, headers and route parameter precedence', async () => {
+    const handler = vi.fn((req: NextApiRequest, res: NextApiResponse) => {
+      expect(req.url).toBe('/api/test?ref=search&tag=one&tag=two&empty=')
+      expect(req.headers['x-custom']).toBe('value')
+      expect(req.query).toEqual({ ref: 'route', tag: ['one', 'two'], empty: '' })
+      res.end('ok')
+    })
+
+    await toWebHandler(handler)({
+      request: new Request('http://localhost/api/test?ref=search&tag=one&tag=two&empty=', {
+        headers: { 'X-Custom': 'value' },
+      }),
+      params: { ref: 'route', omitted: undefined },
+    })
+
+    expect(handler).toHaveBeenCalledOnce()
+  })
+
+  it.each(['%', '%ZZ', '%E0%A4%A', '%FF'])(
+    'preserves undecodable cookie values: %s',
+    async (bad) => {
+      const handler = vi.fn((req: NextApiRequest, res: NextApiResponse) => {
+        expect(req.cookies).toEqual({ bad, good: 'hello world', token: 'a=b', empty: '' })
+        res.json({ success: true })
+      })
+
+      const response = await toWebHandler(handler)({
+        request: new Request('http://localhost/api/test', {
+          headers: { cookie: `bad=${bad}; good=hello%20world; token=a=b; empty=` },
+        }),
+      })
+
+      expect(response.status).toBe(200)
+      expect(await response.json()).toEqual({ success: true })
+      expect(handler).toHaveBeenCalledOnce()
+    }
+  )
+
+  it('does not hide a body-read failure as invalid JSON', async () => {
+    const request = createRequest('{}')
+    const error = new Error('Body read failed')
+    vi.spyOn(request, 'text').mockRejectedValue(error)
+    const handler = vi.fn()
+
+    await expect(toWebHandler(handler)({ request })).rejects.toBe(error)
+    expect(handler).not.toHaveBeenCalled()
+  })
+
+  it('does not turn a handler SyntaxError into a request parsing error', async () => {
+    const error = new SyntaxError('Handler failed')
+    const handler = vi.fn(() => {
+      throw error
+    })
+
+    await expect(toWebHandler(handler)({ request: createRequest('{}') })).rejects.toBe(error)
+    expect(handler).toHaveBeenCalledOnce()
+  })
+
+  it('passes through a Web Response returned by the handler', async () => {
+    const expected = new Response('direct', { status: 202, headers: { 'x-direct': 'yes' } })
+
+    const response = await toWebHandler(() => expected)({ request: createRequest('{}') })
+
+    expect(response).toBe(expected)
+    expect(await response.text()).toBe('direct')
+  })
+
+  it('keeps streamed responses open for chunks written after the handler returns', async () => {
+    let finish: (() => void) | undefined
+    const response = await toWebHandler((_req, res) => {
+      res.writeHead(202, { 'content-type': 'text/event-stream', 'x-stream': 'yes' })
+      res.write('first\n')
+      finish = () => res.end('last\n')
+    })({ request: createRequest('{}') })
+
+    expect(response.status).toBe(202)
+    expect(response.headers.get('x-stream')).toBe('yes')
+    const reader = response.body!.getReader()
+    const decoder = new TextDecoder()
+    expect(decoder.decode((await reader.read()).value)).toBe('first\n')
+    finish!()
+    expect(decoder.decode((await reader.read()).value)).toBe('last\n')
+    expect((await reader.read()).done).toBe(true)
+  })
+
+  it('preserves close and aborted events from the request signal', async () => {
+    const controller = new AbortController()
+    const onClose = vi.fn()
+    const onAborted = vi.fn()
+    await toWebHandler((req, res) => {
+      req.on('close', onClose)
+      req.once('aborted', onAborted)
+      res.end('ok')
+    })({ request: new Request('http://localhost/api/test', { signal: controller.signal }) })
+
+    controller.abort()
+
+    expect(onClose).toHaveBeenCalledOnce()
+    expect(onAborted).toHaveBeenCalledOnce()
+  })
+})
diff --git a/apps/studio/compat/next/api.ts b/apps/studio/compat/next/api.ts
index 15e46eac39f..5126da3fdfb 100644
--- a/apps/studio/compat/next/api.ts
+++ b/apps/studio/compat/next/api.ts
@@ -20,9 +20,19 @@ interface RouteCtx {
   params?: Record<string, string | undefined>
 }
 
+class InvalidJsonError extends Error {}
+
 export function toWebHandler(handler: NextHandler) {
   return async ({ request, params = {} }: RouteCtx): Promise<Response> => {
-    const req = await buildRequest(request, params)
+    let req: NextApiRequest
+    try {
+      req = await buildRequest(request, params)
+    } catch (error) {
+      if (error instanceof InvalidJsonError) {
+        return new Response('Invalid JSON', { status: 400, statusText: 'Invalid JSON' })
+      }
+      throw error
+    }
     const { res, finalize } = buildResponse()
 
     const result = await handler(req, res)
@@ -64,7 +74,12 @@ async function buildRequest(
       const eq = trimmed.indexOf('=')
       const name = eq >= 0 ? trimmed.slice(0, eq) : trimmed
       const value = eq >= 0 ? trimmed.slice(eq + 1) : ''
-      cookies[name] = decodeURIComponent(value)
+      cookies[name] = value
+      try {
+        cookies[name] = decodeURIComponent(value)
+      } catch {
+        // Next's cookie parser keeps values that cannot be URI-decoded.
+      }
     }
   }
 
@@ -82,15 +97,23 @@ async function buildRequest(
   }
 
   let body: unknown = undefined
-  if (method !== 'GET' && method !== 'HEAD' && request.body) {
-    const contentType = request.headers.get('content-type') ?? ''
-    if (contentType.includes('application/json')) {
+  if (method !== 'GET' && method !== 'HEAD') {
+    const contentType = (request.headers.get('content-type') ?? '')
+      .split(';', 1)[0]
+      .trim()
+      .toLowerCase()
+    if (contentType === 'application/json' || contentType === 'application/ld+json') {
       const text = await request.text()
-      body = text ? JSON.parse(text) : undefined
-    } else if (contentType.includes('application/x-www-form-urlencoded')) {
+      try {
+        // Next treats an empty JSON body as an empty object.
+        body = text ? JSON.parse(text) : {}
+      } catch {
+        throw new InvalidJsonError('Invalid JSON')
+      }
+    } else if (request.body && contentType === 'application/x-www-form-urlencoded') {
       const text = await request.text()
       body = Object.fromEntries(new URLSearchParams(text))
-    } else {
+    } else if (request.body) {
       body = await request.text()
     }
   }