Compare and switch
InboxSpec vs MailSlurp
A dated comparison of inbound allowances, inbox-creation limits, waiting and custom domains, including where MailSlurp is better.
Checked on 24 October 2026
Every MailSlurp fact on this page comes from its public pricing page and documentation on that date, listed under Sources. Prices and plans change, so check their current pages before deciding. If something here is wrong or out of date, tell us at hello@inboxspec.com and we will correct it.
At a glance
| Topic | MailSlurp | InboxSpec |
|---|---|---|
| Price | Free $0, Starter $19.99, Pro $49.99 and Growth $129.99 per month. Enterprise is custom. Annual billing is offered. | Free $0 (500 messages/month), Starter $19 (10,000), Developer $49 (50,000), Team $129 (150,000). Monthly billing only. |
| Inbound volume | Free 500, Starter 1,000, Pro 5,000 and Growth 5,000 received emails/month. Extra usage on Pro and Growth is billed separately; the pricing page does not publish the rate. | 500, 10,000, 50,000 and 150,000 messages/month. |
| Creating inboxes | Counted separately: 100, 250, 1,000 and 5,000 inbox creations/month. Free and Starter are fixed caps. | Not counted or charged. Create a fresh inbox for every test run. |
| Custom receiving domain | Pro: paid separately. Growth: 1 included, more billed separately. | Shared domain on Free. Custom receiving domains on every paid plan: 1 on Starter, 3 on Developer, 10 on Team. |
| People | 1 user on Free, Starter and Pro. 2 included on Growth. | No per-seat fees on any plan. Every plan has the same fair-use ceiling of 1,000 people per workspace. No per-inbox, per-request or MCP charge. |
| Waiting | Server-side wait endpoints that hold the request open and return message previews, not full messages. | POST /v1/messages/wait blocks on the server for up to 285 seconds per call (default 120). Waiting is not metered and not rate limited; concurrent-wait limits apply. |
| Codes and links | Separate calls after the wait: one to fetch the email, then code and link extraction endpoints. | The wait response already contains ranked codes and links classified as verify, sign_in, reset_password, unsubscribe or other. |
| Overage | Billed separately on Pro and Growth. | Optional on paid plans at $1 per 1,000 messages, off until an owner sets a monthly budget. Free never incurs overage. |
Where MailSlurp is the better choice
- It is a much broader product: sending to external addresses, SMS and phone numbers, device rendering, inbox placement tests, email warm-up and AI-based extraction.
- Code extraction has more modes, including pattern, LLM and OCR options.
- Official SDKs in many languages, and Enterprise options such as SAML, audit logs and regional hosting.
Where InboxSpec differs
- One meter: received messages. Creating inboxes, API calls and waiting are not counted, so an isolated inbox per test costs nothing extra.
- The wait response carries the codes and links, so one call replaces wait, fetch and extract.
- A custom domain is included from Starter, and every overage rate is published.
Some limits apply to InboxSpec whichever tool you compare it with:
- InboxSpec is new. Production opened in October 2026, so it has no long operating record.
- It only receives and captures email. It does not send to real recipients, test SMS, render emails in real mail clients or offer annual billing.
- It has no SSO, SOC 2 report or uptime SLA.
- REST and hosted MCP are public. The TypeScript SDK and CLI are reviewed release archives that are not yet on a public package registry.
Sources
All pages read on 24 October 2026. InboxSpec figures come from the pricing page and the wait guide.
Mailosaur, MailSlurp, testmail.app and Mailtrap are trademarks of their owners. InboxSpec is not affiliated with them.