Nitrosend is the better choice than Plunk overall, with 86 out of 100 against Plunk's 67. It wins six of the seven tests: working from your AI assistant, emails in your brand without a designer, the free plan, price, developer tools and track record. The two tie on receipts and newsletters on one plan, which both do. Sending email from an AI agent with Nitrosend takes one hosted connection: point Claude, ChatGPT, Cursor or Codex at api.nitrosend.com/mcp and sign in through OAuth, with nothing installed and no key copied. From there a receipt or reset is sent the moment the agent calls for it, while a newsletter or flow stays a draft, gets a test send, and goes out only after someone approves it in the conversation. Plunk is an open source email platform for developers, with transactional email, campaigns, segments and workflows, that you can use hosted or run yourself. Its MCP server runs on the developer's own machine with a secret key, so it suits a developer at a desk more than an agent starting from nothing. At 20,000 emails a month the two both cost $20, and at a million Nitrosend is $500 where Plunk is $1,000.
Nitrosend vs Plunk, compared
The quick version: seven yes-or-no questions a team usually asks when choosing between the two. A tick means the product does it as described on its own pages today. A dash means the honest answer is not a yes or a no.
Nitrosend and Plunk, side by side
Checked October 1, 2026| Question | Nitrosend | Plunk |
|---|---|---|
| Send from the chatCan an agent send a transactional email without anyone opening the web app? | Yes. Yes, through the MCP server. A single transactional email sends on the call; campaigns and flows stay drafts until approved. | Yes. Yes, through its MCP server. Sends to more than one recipient ask for confirmation first. |
| Hosted MCP serverCan a chat app connect over the web, with no local install? | Yes. Yes. A remote server at api.nitrosend.com/mcp, with OAuth sign-in. | No. No. The official server runs locally through npx with a secret key. |
| Sign up with no personCan an agent create the account and send a first email with no DNS work? | Yes. Yes. Signup is an API call, and each brand gets a ready sender on a Nitrosend subdomain. | No. No. A person signs up, copies the secret key from the dashboard and verifies a sending domain. |
| Campaigns and flows in the same planDo newsletters and automations come with the transactional plan? | Yes. Yes, on every plan including Free. | Yes. Yes. Campaigns, segments and workflows on every plan. |
| Perpetual free planIs there a free plan that does not run out? | Yes. Yes. 8,000 emails up front, then 500 a month. | Yes. Yes. 1,000 emails a month, with Plunk branding. |
| Brand learned from your siteDoes it pick up your logo, colors, fonts and voice without a designer? | Yes. Yes. Brand Kit scans your site, and AI Memory keeps house style. | No. No. Templates are built in its editor or uploaded as HTML. |
| Inbound emailCan it receive and parse email sent to your domain? | Not a yes or no. In beta. An agent inbox on your own domain, enabled by request. | Yes. Yes. It receives email at your verified domain, counted as usage. |
Nitrosend meets 6 of 6 yes-or-no questions on this page, Plunk 4 of 7. Rows marked with a dash are not a yes or no question for that product.
How the two score
Seven tests, 100 points in all, the same tests used on every transactional comparison and ranking on this site. Each product gets a score out of 10 on each test, and each test is worth a set number of points. Nitrosend finishes ahead on the total, 86 to 67. Plunk does not score higher on any test, and the two tie on one plan.
Each test, scored
Points out of 100, scores out of 10, October 1, 2026| What we compared | Points | Nitrosend | Plunk |
|---|---|---|---|
| Works from your AI assistant | 25 | 9 out of 10 | 6 out of 10 |
| Receipts and newsletters on one plan | 15 | 9 out of 10 | 9 out of 10 |
| Emails in your brand, no designer | 10 | 9 out of 10 | 5 out of 10 |
| Free plan | 10 | 7 out of 10 | 5 out of 10 |
| Price | 15 | 10 out of 10 | 9 out of 10 |
| Developer tools | 15 | 10 out of 10 | 8 out of 10 |
| Track record and support | 10 | 4 out of 10 | 3 out of 10 |
| Total score | 100 | 86 out of 100 | 67 out of 100 |
Where each one runs out
Rank 1Nitrosend
86 out of 100Total
- Priced by
- Emails sent
- Free plan
- 8,000 emails, then 500 a month
- Entry plan
- $20 a month, 20,000 emails
- Works from your AI assistant9 out of 10Official MCP server, account signup over the API and a ready-made sender, so an agent sends with no dashboard (docs).
- Receipts and newsletters on one plan9 out of 10Receipts, campaigns and flows share one plan, one API and one allowance, on separate streams (pricing).
- Emails in your brand, no designer9 out of 10Brand Kit reads your site for logo, colors, fonts and voice, and every drafted email uses it (docs).
- Free plan7 out of 108,000 emails up front, then 500 every month, no card and no expiry (pricing).
- Price10 out of 10$20 a month for 20,000 emails on Pro and $500 for a million on Enterprise, with unlimited contacts on every plan (pricing).
- Developer tools10 out of 10REST API with an OpenAPI spec, a typed TypeScript SDK, a CLI, an MCP server, signed event webhooks, idempotent sends and test sends (docs).
- Track record and support4 out of 10A young product from a small team. Dedicated IPs from Ultra, a 99.9% SLA only on Enterprise (pricing).
Nitrosend
Ask your agent for the next campaign
Connect Nitrosend to Claude, ChatGPT, Cursor or Codex, point Brand Kit at your site, and describe the email. Contacts are unlimited on every plan.
Free: 8,000 emails to start, then 500 a month. No credit card.
Start free
Rank 2Plunk
67 out of 100Total
- Priced by
- Emails sent
- Free plan
- 1,000 emails a month
- Paid
- $0.001 per email, pay as you go
- Works from your AI assistant6 out of 10Official MCP server with 23 tools for sending, contacts, campaigns and domain checks, but it runs locally with a secret key a person copies from the dashboard (docs).
- Receipts and newsletters on one plan9 out of 10Transactional email, campaign broadcasts, segments and workflow automation on every plan, at one per-email price (pricing).
- Emails in your brand, no designer5 out of 10A drag and drop editor and reusable templates for every kind of send, but the brand design is yours to build (docs).
- Free plan5 out of 101,000 emails a month free forever, no card, with Plunk branding on the emails (pricing).
- Price9 out of 10Plunk charges $0.001 an email with no base fee, so 20,000 emails cost $20 a month and 1,000,000 cost $1,000 a month on its pay as you go plan (pricing).
- Developer tools8 out of 10REST API with an OpenAPI spec, SMTP, event webhooks, inbound email and open source code you can self-host (docs).
- Track record and support3 out of 10A young open source project, AGPL-3.0 and EU-hosted, with no SLA or dedicated IPs on its pricing page (pricing).
The verdict in short
Nitrosend is the better choice overall, 86 to 67, and it is clearly ahead for a team that runs email from an AI assistant and wants the emails in its own brand.
Nitrosend leads Plunk 86 to 67. George Hartley, Nitrosend's co-founder, says what he built it to be. On The Breakout CEO in August 2026 he gave Nitrosend's first value as "patiently improve the core and, and also invent the future." In the same interview he described how an agent finds Nitrosend on its own: "your agent can find the onboarding skill that is kind of listed." Test both with your own agent on a real email.
Plunk does not score higher on any test, and it ties on receipts and newsletters on one plan. Its strengths sit beside the tests: an SMTP relay, inbound email, and a platform that is open source under AGPL-3.0 and can be self-hosted with Docker Compose.
At a glance
Nitrosend and Plunk are scored here on the same 7 tests, 100 points in all: Nitrosend 86 out of 100, Plunk 67 out of 100. Nitrosend takes its best score on Price and Developer tools (10 out of 10) and its lowest on Track record and support (4 out of 10). Plunk takes its best score on Receipts and newsletters on one plan and Price (9 out of 10) and its lowest on Track record and support (3 out of 10). Plunk does not score higher on any test. Scores are unadjusted, and every Plunk figure was read on its own site on October 1, 2026.
How we scored
Each test is a question with one answer per product, checked against that product's own pages and independent review sites on October 1, 2026. A 10 means the product does the job fully on its standard plans. A 5 means it does part of it, or does it only on a higher plan or in a second product. Plunk prices are list prices in US dollars for its hosted plan, read from its own pricing page at 20,000 and 1,000,000 emails a month.
Works from your AI assistant, 25 of 100. Can an agent inside Claude, ChatGPT, Cursor or Codex go from nothing to a delivered transactional email, and then read back what happened to it, with no person opening the web app along the way? Scored on the first-party MCP server and what its tools cover, a CLI that works in a non-interactive runner, account and sender setup over the API, and listings in the chat apps people already work in. Scored on one written rule for every vendor: a first-party server the vendor runs and that can send counts fully; a third-party wrapper (Zapier, Composio, Kanopi, community servers) counts for less; a server that only drafts or reads counts for less than one that sends.
Receipts and newsletters on one plan, 15 of 100. Can receipts and password resets, and the newsletters and automated flows that follow them, go out from one account, on one bill, through one API, with the two streams kept apart?
Emails in your brand, no designer, 10 of 100. Does the product produce the receipt, reset and welcome emails in your brand's own logo, colors, fonts and voice, or does a developer have to write or buy the HTML template first?
Free plan, 10 of 100. How far can a developer get on the free plan before paying: the monthly volume, the daily ceiling, any one-off starter allowance, and whether the plan is perpetual or a trial that ends.
Price, 15 of 100. What does sending cost at 20,000 emails a month, where most teams start, and at 1,000,000, where a busy product ends up? Scored on list prices in US dollars, paid monthly, at the cheapest plan that covers the volume. Every ranking on this site uses the same fixed scale. At 20,000 emails, $20 or less scores 10, then $25 scores 9, $32 scores 8, $40 scores 7, $50 scores 6, $70 scores 5, $100 scores 4 and $140 scores 3. At 1,000,000, $500 or less scores 10, then $625, $800, $1,000, $1,250, $1,750, $2,500 and $3,500 step down the same way. Anything dearer, or a price given only by quote, scores 2. The score is the average of the two.
Developer tools, 15 of 100. How complete is what a developer builds on: a REST API with an OpenAPI spec, official SDKs across languages, a CLI, an SMTP relay, documented delivery-event webhooks, idempotent sends, a test or sandbox mode, inbound email handling, and how deep the reference docs go?
Track record and support, 10 of 100. How long has it run transactional sending at scale, which deliverability controls can you own (dedicated IPs, suppression, separate streams, a published uptime SLA), and what support comes with the plan?
What each one costs in 2026
Plunk's pricing is one rate for everything. The free plan gives 1,000 emails a month with Plunk branding on the emails and no credit card. Past that, the hosted plan is $0.001 an email, with no base fee, no feature tiers and a monthly spend cap you set. Contacts are unlimited. Self-hosting the open source edition costs nothing from Plunk, and you pay your own infrastructure and delivery.
Nitrosend's pricing is $20 for 20,000 emails on Pro and $500 for a million on Enterprise. Transactional, campaigns and flows draw on the same allowance, and contacts are unlimited too.
At 20,000 emails a month, where most teams start, the two are level at $20. At a million, Nitrosend is $500 and Plunk's flat rate comes to $1,000.
Two of Plunk's billing rules move the real figure. An email with an attachment counts as two, whatever its size, and inbound mail counts against the same allowance as sends. When a monthly cap is reached, sends are refused with a 402 error until the period resets, and inbound mail is dropped rather than queued, so an agent or app that relies on replies needs the cap set with room to spare.
What sending costs at two volumes
List prices, USD, October 1, 2026| Scenario | Nitrosend | Plunk |
|---|---|---|
| 20,000 emails a month | Pro, $20 a month | $20 a month |
| 1,000,000 emails a month | Enterprise, $500 a month | $1,000 a month |
| Add newsletters and a welcome series | Counted in the same allowance, contacts unlimited | Counted at the same per-email rate, contacts unlimited |
Where Plunk fits better
Plunk does not score higher on any of the seven tests and ties one, but it does a few jobs Nitrosend does not. Read these before you choose Nitrosend.
- Pick Plunk if you want open source code, SMTP or inbound email. It has a REST API with an OpenAPI spec, SMTP on ports 587 and 465 and inbound email at your verified domain. The code is open source under AGPL-3.0, so a team can read it, change it and run it on its own servers. Nitrosend is not open source, and it has no SMTP relay and receives email only through an agent inbox that is still in beta.
- Pick either if you want receipts and newsletters on one plan. Plunk matches Nitrosend here, 9 to 9: transactional email, campaign broadcasts, segments and workflows on every plan, at one per-email price.
Plunk also has a serious agent story. Its official MCP server has 23 tools across email, contacts, segments and campaigns. A read-only setting leaves the writing tools out of the server altogether, and billing, project deletion and key rotation need a dashboard session, so no tool can reach them. The gap is in where the agent starts and what the email looks like. The server runs locally through npx with a secret key that opens the whole project, a person signs up and verifies a domain first, and the design is whatever the team builds in the editor.
The confirmation step is the detail that decides agent work. Plunk asks before a campaign, or an email to more than one recipient, goes out, and its MCP guide says the answer has to come from the person through the chat app, not from the model: a client that cannot show a prompt cannot send. With someone watching in Claude Desktop or Cursor, that is a strong check. In a scheduled job or a CI runner nobody is there to answer, and the documented route is a setting that skips the confirmation for headless automation, so the check is switched off rather than moved. Nitrosend keeps its checks on the server as separate calls. A campaign is approved, which checks its content and readiness, then set live, and a send to every contact needs its own confirmation flag. Its MCP workflow examples add that Safe Mode can still block a campaign going live or being scheduled from an API key, which is the call an unattended runner makes.
On Nitrosend an agent can also start from nothing: the MCP server is hosted with OAuth, the account is one API call, and a ready sender is waiting on a Nitrosend subdomain.
Moving from Plunk to Nitrosend
- Let the agent learn the brand. Point Brand Kit at your website and every email the agent drafts uses the logo, colors and fonts it found. The transactional template guide covers what each receipt and reset needs.
- Keep an approval step. Plunk asks before a campaign sends. Nitrosend has test sends, and campaigns and flows stay drafts until approved. Hold the first large send until someone has read the test copy.
- Self-hosted on Amazon SES? Keep the account. A self-hosted Plunk already sends through the team's own SES account, because Plunk's self-hosting guide requires one. Nitrosend accepts your own SES account as its sending provider on paid plans, so the quotas, reputation and region stay where they are. The IAM user is the part to redo. Plunk's SES setup asks for a policy of seven SES actions, while Nitrosend's connection test builds its own bounce and complaint topic and configuration set, so its docs call for the AmazonSESFullAccess and AmazonSNSFullAccess managed policies and publish no narrower one. Stay in the same region too: AWS keeps sandbox status per region, and a sandboxed region can only send to verified addresses.
- Plan around the gaps. If you rely on inbound email, SMTP or self-hosting the platform itself, keep Plunk for that part. Hosted Plunk is not one of the providers Nitrosend accepts as a bring-your-own sending key. The difference between transactional and marketing email explains why the two streams stay apart either way.
Which one to pick
Pick Nitrosend if an agent should set up, write, design and send the email from the assistant the team already uses, starting from nothing, in the brand's own look, or if an agent runs unattended and the send checks should stay on. It scores higher overall, 86 to 67, and costs half as much at a million emails a month. The Nitrosend MCP server and the ChatGPT app are the two ways most teams start, and transactional email is the primer on what belongs in which stream.
Pick Plunk if you want open source code you can self-host, inbound email, or an SMTP relay, and your developers are happy to build the email design themselves.
Nitrosend vs Plunk FAQ
Yes. 1,000 emails a month, free forever, with Plunk branding on the emails (Plunk pricing). Nitrosend's Free plan gives 8,000 emails up front and then 500 every month, with no expiry and no credit card.
At 20,000 emails a month the two are level at $20. At a million Nitrosend Enterprise is $500 against $1,000 on Plunk's flat rate. Self-hosting Plunk has no Plunk fee, but you run and pay for the infrastructure and delivery.
Yes. Plunk's official MCP server has 23 tools for email, contacts, segments and campaigns, and asks the person in the chat app before a send to more than one recipient. It runs locally with a secret key. Nitrosend's MCP server is hosted and signs in with OAuth, and an agent can create the account and send with no DNS work.
Add the Nitrosend MCP server at api.nitrosend.com/mcp in Claude's connector settings and sign in with OAuth in the browser; no key is pasted and no package is installed. Ask for a test send to your own address first. A transactional email then goes out on the call, while a campaign or flow stays a draft until you approve it. ChatGPT, Cursor and Codex connect to that one address the same way, as the Nitrosend MCP docs show.
Yes, under AGPL-3.0, and it can be self-hosted with Docker Compose on your own Amazon SES account. A team that changes the code and lets other people use its version over a network must offer them the changed source, under section 13 of the AGPL. Nitrosend is a hosted platform.
This review does not score it, because neither product publishes a comparable inbox-placement number. Whichever you use, reputation belongs to the sending domain, so authenticate it and keep transactional and marketing mail on separate streams.