A temporary email service hands you a working inbox you never signed up for: open the site, an address is generated, and mail sent to it appears in your browser until it expires. For developers it's a testing primitive — a real, programmable inbox for signup flows, magic links, OTP verification, and free-trial cycling without polluting your Gmail. Here are the nine free temp email tools worth using in 2026, and which expose a clean HTTP API for end-to-end automation.

Why Developers Need Disposable Email

• End-to-end signup testing — register a fresh user, click the confirmation link, verify the welcome email arrived. Needs a real, programmable inbox per run.
• Magic-link and OTP flows — Supabase Auth, Clerk, Auth0 passwordless all send a one-time link or code you must actually fetch.
• Free-trial cycling and spam avoidance — a clean inbox per trial, and getting past email-gated whitepapers without follow-up campaigns.
• Agent automation — an AI agent registering an account on a user's behalf generates an address, polls the inbox over HTTP, extracts the verification link, and continues — no human, no real inbox at risk.

Every address below was sent test mail from Resend, Brevo, and Gmail in April 2026 and received it; each requires no registration for the basic flow and has a sane UI or documented API.

1. Mail.tm — Best Free Temp Email API

Mail.tm is the best free disposable provider for automated testing. Clean web UI, but the killer feature is a fully documented JSON API — create accounts, list messages, fetch bodies over HTTP, no scraping and no API key. You POST /accounts with a generated address and password, get a JWT, and read your own inbox. Addresses persist as long as you use them, with no aggressive rate limiting on normal test volumes.

import requests, secrets

BASE = "https://api.mail.tm"

# 1. Available domains
domain = requests.get(f"{BASE}/domains").json()["hydra:member"][0]["domain"]

# 2. Create an inbox
address = f"{secrets.token_hex(8)}@{domain}"
password = secrets.token_urlsafe(16)
requests.post(f"{BASE}/accounts", json={"address": address, "password": password})

# 3. Authenticate
token = requests.post(f"{BASE}/token", json={
    "address": address, "password": password,
}).json()["token"]

# 4. Poll the inbox
headers = {"Authorization": f"Bearer {token}"}
messages = requests.get(f"{BASE}/messages", headers=headers).json()
print(messages)

That snippet is the entire integration. Drop it into a Playwright fixture and each test gets a fresh inbox — no shared state, no flakiness. Best for: end-to-end tests and AI agents that need to receive verification email without an API key.

2. Mailinator — Public Inbox With a Pro API

Mailinator is the oldest still-maintained service and the most developer-oriented. The free tier uses the shared public domain @mailinator.com — anyone who knows the username reads the mail, so generate a long random one and treat the inbox as a write-once log. The public inbox is browser-only. The paid tier ($59/month) adds private domains and a clean REST API (api.mailinator.com), but free public flow covers most testing. Best for: teams already on Mailinator, manual QA where username obscurity is enough.

3. Temp-Mail.io — Big Domain Pool, Browser-Friendly

Temp-Mail.io is the polished consumer option — dozens of rotating domains, multiple lifetimes, Chrome and Firefox extensions for a one-click address. Open the page and an address is already created. There's a paid RapidAPI-hosted JSON API, but the public web flow exposes no free API. Best for: manual signup testing and browser-driven research.

4. 10 Minute Mail — The Classic Quick Hit

10 Minute Mail is the original "open the page, address ready, ten-minute timer" service (extendable by another ten minutes). No API, no extension — just one address and one inbox view. That minimalism is the point. Best for: one-off email gates, download links, never-coming-back signups.

5. Guerrilla Mail — Long-Running and Reliable

Guerrilla Mail has been online since 2006 and keeps mail for one hour by default. It exposes a documented JSON API with session tokens — older and quirkier than Mail.tm's (set a user via set_email_user, poll get_email_list) but works without registration.

import requests

BASE = "https://api.guerrillamail.com/ajax.php"
session = requests.Session()

addr = session.get(BASE, params={"f": "get_email_address"}).json()
print("Inbox:", addr["email_addr"])

emails = session.get(BASE, params={"f": "get_email_list", "offset": 0}).json()
print(emails["list"])

Best for: free programmatic inbox without account creation; longer test scenarios needing up to an hour.

6. YOPmail — Predictable Inbox Names

YOPmail works differently: every @yopmail.com address already exists — you just type it. No creation step, no tokens, no sessions; pick a unique-enough username (a UUID works) and use it. Inboxes hold mail for eight days, far longer than most rivals. The flip side: anyone who types the same name reads the mail. Best for: predictable manual test inboxes, or automation with pre-generated UUID local-parts.

7. EmailOnDeck — Slightly More Legit-Looking

EmailOnDeck uses domains that look less obviously disposable — useful against aggressive temp-mail blocking. A small CAPTCHA on the free flow prevents pure automation but is fine manually. A paid plan (around $5/month) adds longer-lived addresses and better rotation. Best for: manual sign-ups for services that block obvious temp domains.

8. Mail7 — Built Specifically for QA

Mail7 is built for testing — its homepage leads with Selenium and Cypress. Its REST API lets you create custom addresses (you control the local part), poll the inbox, and pull the full HTML/text body, authenticated by a free API key. The free plan handles a few hundred messages/day. More QA-shaped than Mail.tm: name inboxes by feature (checkout-test-1@...) and reuse them across runs. Best for: CI pipelines wanting named, reusable inboxes.

9. SimpleLogin (by Proton) — Real Aliases, Not Throwaway

SimpleLogin is an email aliasing service, now owned by Proton. Instead of throwaway inboxes, you create aliases that forward to your real inbox and disable any that start receiving spam. The free tier gives 10 aliases on the shared simplelogin.com domain, no card; the paid tier ($30/year) lifts that to unlimited on custom domains. It won't help with automated testing — the point is forwarding to your real inbox — but it's the closest thing to a long-term, ethical alternative to disposable email. Best for: long-term personal use and Proton ecosystem users.

Comparison Table

End-to-End Testing With Mail.tm and Playwright

A full Playwright test that signs up for a service, fetches the verification email from Mail.tm, clicks the link, and asserts the dashboard loads — the test most teams skip because writing it against Gmail is painful:

// signup.spec.ts
import { test, expect } from "@playwright/test";

const MAIL_BASE = "https://api.mail.tm";

async function createInbox() {
  const domains = await fetch(`${MAIL_BASE}/domains`).then(r => r.json());
  const domain = domains["hydra:member"][0].domain;
  const address = `e2e-${crypto.randomUUID().slice(0, 8)}@${domain}`;
  const password = crypto.randomUUID();

  await fetch(`${MAIL_BASE}/accounts`, {
    method: "POST",
    headers: { "Content-Type": "application/json" },
    body: JSON.stringify({ address, password }),
  });
  const { token } = await fetch(`${MAIL_BASE}/token`, {
    method: "POST",
    headers: { "Content-Type": "application/json" },
    body: JSON.stringify({ address, password }),
  }).then(r => r.json());

  return { address, token };
}

async function waitForLink(token, timeoutMs = 30_000) {
  const headers = { Authorization: `Bearer ${token}` };
  const start = Date.now();
  while (Date.now() - start < timeoutMs) {
    const list = await fetch(`${MAIL_BASE}/messages`, { headers }).then(r => r.json());
    const first = list["hydra:member"][0];
    if (first) {
      const full = await fetch(`${MAIL_BASE}/messages/${first.id}`, { headers }).then(r => r.json());
      const match = full.text.match(/https?://S+verifyS*/);
      if (match) return match[0];
    }
    await new Promise(r => setTimeout(r, 2000));
  }
  throw new Error("No verification email arrived");
}

test("user can sign up and verify email", async ({ page }) => {
  const { address, token } = await createInbox();
  await page.goto("https://example-app.com/signup");
  await page.fill("input[name=email]", address);
  await page.fill("input[name=password]", "TestPass123!");
  await page.click("button[type=submit]");
  const link = await waitForLink(token);
  await page.goto(link);
  await expect(page.locator("h1")).toHaveText("Welcome");
});

A full real-world signup flow tested end-to-end with no shared inbox state and no human. Run it ten times in parallel in CI and every test gets its own inbox.

Privacy, Security, and Common Mistakes

• Public inboxes are public. Mailinator's free tier and YOPmail's entire model expose every message to anyone who guesses the local part — never use them for password-reset mail on accounts you care about.
• Account-based services aren't encrypted. Mail.tm, Guerrilla Mail, and Mail7 store mail in plaintext; treat it as readable by the operator.
• Many SaaS apps block disposable domains. For block-happy targets (Stripe, banking, KYC) use a private alias (SimpleLogin) or a paid custom-domain tier.
• Create a fresh address per test. Sharing one inbox across parallel tests that expect "the latest email" causes collisions.
• Poll every two to five seconds, not twenty times a second, and set a timeout (30s for most flows, 90s for sluggish ESPs) so "email never arrives" fails loudly.

Frequently Asked Questions

Which temp email service has a free API with no key?

Mail.tm and Guerrilla Mail both expose a JSON REST API with no API key — you authenticate with a per-inbox token you generate yourself. Mail7 also has a free API but requires a free key from its dashboard.

Do temp email services work when a site blocks disposable domains?

Often not — many SaaS apps maintain blocklists. Use EmailOnDeck's less-obvious domains, or a private alias/custom-domain tier (SimpleLogin, paid Mailinator or Mail7) when the target actively blocks temp mail.

Is temporary email private?

No. Public inboxes (Mailinator free, YOPmail) are readable by anyone who knows the address, and account-based services keep mail in plaintext. Temp email is a development and research tool, not an identity replacement.

Final Recommendation

If you remember three: Mail.tm for any test automation (free, no key, JSON, works), 10 Minute Mail for a manual address right now, and SimpleLogin for protecting your real inbox long-term. Disposable email looks small until you build a real automated test suite and realize it's load-bearing. Pick one, wrap a thin helper around its API, and stop thinking about email infrastructure for the rest of the year.