CampaignStack vs Reply.io, compared for agencies

Breadth is the product, and Reply.io has more of it than anyone in this comparison. One sequence can hold an email, a LinkedIn touch, a call, an SMS and a WhatsApp message, branching on opens, replies and LinkedIn activity. The email side comes with unlimited mailboxes, warm-up on every one of them, a deliverability kit the vendor counts at more than 30 features, and domain purchase from inside the product. The data side is a database of more than a billion contacts and 60 million companies, with hiring and technographic intent attached, and 50 live data credits a month on every standard plan.

Jason, the AI SDR, is a complete loop rather than a writing feature: it writes an ICP, finds prospects from a prompt, drafts each step from your playbooks and knowledge base, answers replies in your voice, and books meetings against a live calendar. Two details deserve the credit. Every draft links the sources it used, so a reader can check the claim rather than trust it, and approval mode puts a person in front of every send when you want one. The agent surface is the other piece of real work: a REST API, a CLI, installable skills and an MCP server with 70 tools, each annotated read-only or destructive so a model can gate its own risky calls, all on one scoped key. On the LinkedIn side, unanswered invitations are withdrawn automatically after a wait you set, which most tools in this set leave to you.

Reply.io's LinkedIn limits are per action type and configurable: a fixed maximum or a random range for connection requests, messages, InMails, profile views, likes, comments, follows and endorsements, with a delay window between actions. By default the vendor's algorithm sets them. The ceiling is yours to raise, and the vendor's own guide to LinkedIn messaging recommends 50 to 80 connection requests a day. LinkedIn's practical cap is around 100 a week. A tool that documents a daily number above the platform's weekly one is asking you to be the safety system, which is fine for an operator who knows the numbers and a problem for an agency putting a client's account in the hands of whoever configured it last.

CampaignStack computes the ceiling instead of asking for it. Connection requests are capped at a percentage of the account's connections per day under a weekly cap, every action type warms up from a fraction of its limit, sends are paced across business hours with a start time that moves daily, and the first security check pauses that action family for a day. The account connects with a session cookie consumed into an encrypted browser profile behind one static residential proxy. Reply.io takes a cookie through its browser extension, or LinkedIn credentials, and the API exposes both; where the automated session runs from, and on what IP, is not something its documentation says, so we will not guess for it.

Jason decides who to prospect once, at the top: an ICP written from your value proposition, a search run against Reply Data, a list. What Reply.io does not document is a score that lives on a lead and keeps deciding after that. In CampaignStack every lead is scored against every campaign's ICP and the score gates membership, so a job change, a funding round or a post the lead engaged with yesterday moves them into or out of a campaign without anyone rebuilding a list. Reply.io's signals are intent data attached to its database, useful for finding new people; ours watch the people you already hold.

On the draft itself, Reply.io's answer is a person in approval mode and source links to check. Both are good, and the review queue here does the same job. The difference is what happens before the person. Every CampaignStack draft is read by a critic model against the full brief it was written from, and a draft that keeps failing ships flagged and pinned to the top of the queue with the objection attached. Reviewing ten drafts a day is a habit; reviewing two hundred is a job nobody keeps up, which is why the second reader has to be a machine.

Reply.io's agency plan is a base of $210 a month with unlimited clients and users, and $69 a month for each LinkedIn account you automate; the comparison table lower on the same pricing page quotes the agency entry at $166, so ask which one you are signing. CampaignStack is $299 a month per client workspace with every LinkedIn account and team member inside it, $249 on annual billing. Divide $299 by $69 and the lines cross at a little over four automated LinkedIn accounts per client, before Reply.io's base: below that, Reply.io is cheaper per client, above it CampaignStack is. If you want the AI to draft and handle replies for each client, Reply.io's Agency AI SDR is $500 a month per client, and that is the number to put against $299.

What the two prices buy is different, and the arithmetic hides it. Reply.io's $69 buys a channel on a sequence you fill and configure. CampaignStack's $299 buys the workspace that decides who fills it, meters what each account can safely do today, reads every draft and holds the doubtful ones. If your team already does that deciding well by hand, pay Reply.io. If those hours are what you are trying to get back, the price per workspace is the cheaper one.