Smartlead API review
Best sending infrastructure
GET https://server.smartlead.ai/api/v1/campaigns/?api_key=$KEY # the key travels as a query parameter, not a header # 60 req/min and 1,000/hour on Standard, per API key # unlimited email accounts on every plan, including Base # but Base has no API and no webhooks at all
Smartlead is a cold email platform that made one decision differently from almost everyone else: it does not charge per mailbox. Every plan, including the $39 Base plan, carries unlimited email accounts and unlimited warmup, and the meters are volume instead. That is the right way round for deliverability work, because the setup that keeps you out of spam is the one that spreads sending across many domains and inboxes, and a per-mailbox price punishes exactly that.
The catch is where the Smartlead API sits. It is not on Base. The API and webhooks both start at Pro, which is $94 a month, so the entry price for anything programmatic is more than twice the headline figure. That is worth stating plainly because the $39 number is the one that appears in every comparison, and it buys a product you cannot build against.
What you get from Pro upward is a straightforward REST surface at server.smartlead.ai, authenticated with an API key passed as a query parameter rather than a header. The Smartlead API rate limits are published properly, and they have a second layer that most integrations discover the hard way.
The rest of the category is in the Sending APIs listing.
What the plans actually meter
Smartlead runs three separate counters, and the plan that looks generous on one is often the tight one on another. These are the monthly figures from its own pricing page.
| Plan | Monthly | Contacts | Sends a month | API |
|---|---|---|---|---|
| Base | $39 | 2,000 | 6,000 | No API, no webhooks |
| Pro | $94 | 30,000 | 90,000 | API and webhooks |
| Unlimited Smart | $174 | Unlimited | 150,000 | API and webhooks |
| Unlimited Prime | $379 | Unlimited | 500,000 | API and webhooks |
Annual billing takes 17% off all four, so Pro is $78.33 a month paid yearly. The third counter is verified prospect emails, the leads sourced through SmartProspect: 2,000 on Base and 30,000 on Pro, both as a $59 a month add-on, then 50,000 and 170,000 included on the two Unlimited tiers. That add-on is the reason Pro plus data is $153 a month rather than $94, and it is the line most comparisons leave out.
Smartlead counts a stored unique prospect against the contacts limit and each individual email against the sends limit, and the two move independently. Base allows 2,000 contacts and 6,000 sends, which is three emails per contact: fine for a three-step sequence and not enough for a five-step one. Work out your sequence length first, multiply, and then pick the plan, because the upgrade you get pushed into is usually priced on the counter you were not watching.
Smartlead API pricing, plan by plan
Smartlead API pricing is not a separate line item, but it is not free either: the API arrives with the Pro plan and there is no way to buy it onto Base.
Base
- Unlimited email accounts and warmup
- 2,000 contacts, 6,000 sends a month
- No API, no webhooks, no CRM
Pro
- The first tier with API and webhooks
- 30,000 contacts, 90,000 sends
- Client workspaces at $29 each, SmartServers at $39
Unlimited Smart
- Unlimited contact storage, 150,000 sends
- 50,000 verified prospect emails included
- Premium warmup pool and CSM access
Unlimited Prime
- 500,000 sends, 170,000 verified emails
- 3 SmartServers and 3 client workspaces included
- Dedicated manager and a private Slack channel
There is no free tier, but every plan has a free trial with no card. Mailboxes can be bought inside the product through SmartSenders, from $13 a year per domain and $4.50 a month per fresh Google mailbox, roughly doubling to $18 and $9 for pre-warmed. Email verification is sold as credit packs from $32, and SmartDelivery inbox placement testing is a separate subscription from $49 a month.
Every roundup quotes Smartlead at $39 a month, and that figure is correct for the product. It is wrong for anybody reading this page. Base has neither the API nor webhooks, so a build that needs to push leads in or react to a reply starts at Pro. Against Instantly, which puts its API on the $47 Outreach plan, that is the single number that decides most comparisons, and it is twice as far apart as the headline prices suggest.
Two layers, and the second one has no headers
Smartlead API rate limits are published per API key rather than per account, and they come in two layers that stack. The plan-wide limit covers every endpoint together. A handful of expensive endpoints then carry their own limit on top, which having plan quota left over does not let you exceed.
| Tier or endpoint | Limit | What it covers |
|---|---|---|
| Standard | 60/min, 1,000/hour | Burst 10 requests a second. All endpoints combined. |
| Pro | 120/min, 3,000/hour | Burst 20 a second. Same shared scope. |
| Enterprise | Custom | Negotiated. |
| campaigns/{id}/leads-statistics | 10 per 60s | Per account, across every campaign. |
| campaigns/all-leads-activities | 10 per 60s | Per account. |
| analytics/mailbox/domain-wise-health-metrics | 10 per 60s | Per account. |
The plan-wide 429
Machine readable.
- Returns JSON with a RATE_LIMIT_EXCEEDED code and a retry_after in seconds.
- Carries Retry-After and the three X-RateLimit-* headers.
- Smartlead suggests holding your client to 80% of the limit, so 48 a minute against 60.
- Exponential backoff on repeated failures, which the docs give sample code for.
The endpoint 429
Not machine readable.
- Returns a plain text body, not the JSON shape, so a parser expecting JSON breaks.
- Carries no Retry-After and no X-RateLimit-* headers at all.
- Smartlead's own advice is a fixed wait of up to 60 seconds, because nothing tells you.
- Each of the three has its own counter, so they do not eat each other's budget.
The three endpoint limits are per account and they do not move when you upgrade. A dashboard that polls lead statistics across 20 campaigns hits 10 requests a minute whether you pay $94 or $379, and the 429 it gets back has no header telling it when to try again. The fix Smartlead documents is to stop polling and start filtering: pass event_time_gt on leads-statistics and the date range on the analytics endpoint, request the largest page size, and make each of your ten calls do as much work as it can.
How to create a Smartlead API key
Smartlead sends the API key as a query parameter rather than an Authorization header, which works everywhere and leaves the key in places you may not want it.
Getting the Smartlead API key
One per account, plus client keys.
- Open the Smartlead app, then Settings, and copy the key from the API section.
- Append it to every request as ?api_key=YOUR_KEY.
- Agencies on Pro and above can issue a client-level key per workspace.
- An invalid key comes back as {"message": "Invalid API Key"} rather than a 401 shape.
Why the query parameter matters
Worth handling deliberately.
- A key in a URL lands in server access logs, proxy logs and browser history.
- It also lands in any error tracker that records the failing request URL.
- Rate limits are per key, so a second key is a second budget, unlike Instantly.
- Rotate by issuing a new key and switching, since there is no documented expiry.
Where the Smartlead API documentation lives
The Smartlead API documentation lives at api.smartlead.ai, built on Mintlify, so any page returns Markdown if you append .md and there is an index an agent can read. The Smartlead API docs include working cURL, Python, JavaScript and PHP for each endpoint, which is more than most senders ship. The product is smartlead.ai, so both names refer to the same API.
| Surface | Where | What it answers |
|---|---|---|
| Introduction | api.smartlead.ai/introduction | The base URL and the first authenticated call. |
| Rate limits guide | api.smartlead.ai/guides/rate-limits | Both layers, the headers, and the backoff code. |
| Best practices | api.smartlead.ai/guides/best-practices | Polling, filtering and page sizes. |
| API base | server.smartlead.ai/api/v1/ | Where the requests go. |
| Webhooks | Help center, "resolve webhook failures" | Retry behavior when your endpoint is down. |
| Client keys | Help center, "client level API keys" | How an agency scopes a key to one workspace. |
There is no official SDK, so integrations are direct REST calls against v1. Webhooks are the right way to hear about replies rather than polling, and they arrive with the API at Pro, which is another reason the Base plan is not a starting point for a build.
Smartlead also ships an MCP server, and it is on the MCP page with the others in this directory.
Smartlead's own walkthrough of the API
Smartlead publishes this on its own channel, so it is Smartlead's account of Smartlead, not ours. It is here because a rate card cannot show you the thing moving, and a few minutes of the product is faster than any paragraph on this page at telling you whether the shape of it fits yours.
YouTube · Smartlead Leveraging the Smartlead API: my top 5 Smartlead API endpoints 14:11 · Published May 2024Not Smartlead staff: an agency founder walks through the five endpoints he uses most, which is why it is the most useful video on the channel for this page. It sits on Smartlead's own channel, so they are publishing it, and the 500 hours and 50 integrations are his figures.
Published 10 May 2024 on Smartlead, the channel Smartlead's own pages link to, and read on 13 October 2026. Nothing in it is a source for a price or a limit on this page: every figure in the tables above comes from a Smartlead page.
Strengths and limits
Smartlead is the sending infrastructure play in this directory, and it is priced for volume rather than for seats.
What it does well
- Unlimited email accounts and unlimited warmup on every plan, including Base.
- No per-seat and no per-mailbox charge anywhere in the rate card.
- Rate limits published in full, both layers, with backoff code in the docs.
- Rate limits are per API key, so a second integration gets its own budget.
- Automatic sending rotation across every connected mailbox in a campaign.
- Mailboxes, domains, verification and inbox placement testing all buyable inside the product.
- Agencies get client workspaces at $29 and client-scoped API keys.
- SOC 2 Type II as well as a GDPR DPA.
Where it falls short
- No API and no webhooks on the $39 Base plan, so the real entry price is $94.
- The API key travels as a query parameter, which puts it in logs.
- Three analytics endpoints are capped at 10 calls a minute on every plan.
- Those endpoint 429s carry no Retry-After and no rate limit headers.
- Verified prospect emails are a $59 add-on on Base and Pro.
- The MCP server speaks SSE only and works in Claude Desktop, not yet in Claude on the web.
- No official SDK.
- No free tier, only a trial.
Where Smartlead data comes from, and what you may do with it
The question that arrives late and expensively is not how good the data is, it is who is allowed to hold it. These are the fields each one returns, the coverage it claims and the compliance it publishes.
| Provider | Fields returned | Coverage | Compliance | Redistribution |
|---|---|---|---|---|
| Smartlead | Work email, CRM records | Global | GDPR DPA SOC 2 Type II | Not stated |
None of these states a redistribution position on its pricing or docs pages. Internally that never matters. Put the rows in something your customers can see and it becomes the question your legal team asks first.
Two practical notes that apply to every provider on this page. A compliance badge describes the vendor, not your use of it, so a GDPR DPA does not give you a lawful basis for the outreach you send. And every one of these vendors runs its own opt-out, which means a person who asks you to delete their record has to be removed from your copy as well as from theirs.
If Smartlead is not the answer
Four providers in the Sending APIs listing that solve the same problem differently. Each one is a trade, and the trade is named.
Instantly
$47/moThe direct like-for-like: unlimited email accounts and warmup from $47 a month, with the API on every plan rather than from the second tier.
Apollo
$49/seat/moSequencing bundled with search and enrichment on one $49 seat, with API access on a free plan. The move if you were buying data separately anyway.
Salesloft
Quote onlyThe enterprise end of the same job, with a well documented cost-per-minute API. No published price, so expect a sales conversation.
HubSpot
Free tierIf sequencing really belongs next to the CRM, HubSpot does both and includes API access on a genuinely free tier.
The full set, organized by the reason people leave, is on the Smartlead alternatives page.
Smartlead against the obvious rival
Same rate cards, read side by side, with the arithmetic done on a worked volume rather than left to you: Smartlead vs Apollo, Smartlead vs Instantly and Smartlead vs lemlist.
The same again, against the rest of the field: Smartlead vs Saleshandy, Smartlead vs QuickMail and Findymail vs Smartlead. Every pairing in the directory is on the compare hub.
Smartlead vs Apollo
CompareDedicated sending infrastructure against sending bundled with the data.
Smartlead vs Instantly
CompareThe two senders that both give you unlimited mailboxes, gating the API in opposite ways.
Smartlead vs lemlist
CompareThe API starts at $94 on one and $55 on the other, and the cheaper one throws in a CLI.
Before you build against it
Four things to settle first, each one read off Smartlead's own pages. The ticks are remembered in this browser, so you can come back to a half-finished integration.
Who should actually buy this
Buy Smartlead if you are running cold email at volume across a lot of inboxes and you intend to pay for Pro. Unlimited mailboxes with warmup included, no per-seat charge, and automatic rotation across every connected account is the correct shape for deliverability work, and at $94 a month for 30,000 contacts and 90,000 sends it is good value against anything comparable. The infrastructure add-ons matter too: being able to buy domains and pre-warmed mailboxes inside the product removes a whole procurement step.
Do not buy the Base plan if you are reading this page. It is a perfectly reasonable $39 product for someone running campaigns by hand, and it is useless as an integration target, because it has neither the API nor webhooks. The comparison worth doing is Smartlead Pro at $94 against Instantly Outreach at $47, where Instantly gives you the API immediately and Smartlead gives you roughly thirty times the volume allowance.
On the API itself, design for the second layer of limits before you design for the first. The plan-wide 60 a minute is generous and well behaved, with headers and a retry delay you can read. The three analytics endpoints at 10 a minute are neither, and they are the ones a reporting integration will hit. Filter by event time, take the biggest page you can, and never build a dashboard that polls them on a loop.
Smartlead is one of the providers in the hiring signal to outbound and inbound speed to lead stacks on this site, where the cost is worked out end to end.
Unlimited mailboxes are worth nothing if the list is wrong.
Deliverability is the easy half. Frontal builds the signal, the targeting and the copy that make the sending worth paying for, inside your own stack.
Worked with 300+ companies. A senior operator runs your account.
What Smartlead users say, in their own words
The one part of this page that is not a vendor claim. Quotes are transcribed as written and linked to the thread.
The sending tool is not what decides deliverability
To be clear, instantly Apollo and smartleads are all just front end management tools for campaign, lead list, and sending triggering through any API/SMTP servers (like Gmail, M365, sendgrid, SES, etc.) and they shouldn't have a direct effect on deliverability. Your email copy, leads, and sending patterns/volume are what matters the most
r/Emailmarketing · June 2024 · 5 points
The most useful correction on this page, and it applies to every sending provider in the directory rather than to Smartlead alone. These products schedule, rotate and report; the mail still leaves through Google, Microsoft or an SMTP relay, and the things that decide placement are the domain, the authentication, the list and the volume curve.
What that means for a comparison like this one is that the feature lists are not where the difference lives. Compare the mailbox economics, the webhook surface and what the API lets you automate, because those are the parts the vendor actually controls.
14 threads read on 13 October 2026, searched by vendor name. Scores and dates are the comment's own. Nothing here is the only source for a price or a limit on this site: every figure in the tables above comes from a vendor's own page.
Smartlead API, answered
Is the Smartlead API free?
No. No free tier. Free trial, no card. API access starts at the Pro plan.
How much does the Smartlead API cost?
Smartlead starts at $39/mo. Billing is subscription. Read from Smartlead's own pricing page on 19 October 2026.
What are the Smartlead API rate limits?
60 req/min and 1,000/hour per key, 120 and 3,000 on Pro. Three endpoints capped at 10 a minute on top.
How do I get a Smartlead API key?
API key as a query parameter. The current steps are in Smartlead's own documentation, which is authoritative on anything that has changed since 19 October 2026.
Does Smartlead have an MCP server?
Yes, at https://mcp.smartlead.ai/sse. It is listed with the others on the MCP page.