CampaignStack vs Sinky, compared for agencies

For 49 euros a month, Sinky puts the whole prospecting loop in one screen: five ways to source a list, a sequence that engages before it asks, a second channel when the first goes quiet, an inbox that sorts replies by importance and suggests the answer, a pipeline that moves itself as conversations progress, and a copilot that turns the day into a to-do list. Team seats cost 147 euros for three, an extra LinkedIn account costs 5 euros, and the vendor migrates your leads and history from your old CRM for free. Its own agency customers describe SDRs spending two to three times less per exchange, which is the right thing to sell an agency on.

WhatsApp is a real differentiator in the French market it serves, and the site's line, email to open, LinkedIn to convince, WhatsApp to close, is a coherent sequence design rather than a channel list. The AI suggestions stay editable by design, which the FAQ states plainly: the copilot is an assistant, not a closed automatic system.

Read every page on sinky.ai and three things stay unanswered. How a LinkedIn account connects: the FAQ says you connect it and pay 5 euros for a second one, and never says whether that is a cookie, a password or an extension, nor where the session runs or on what IP. What the limits are: the LinkedIn page says volumes, delays and sequencing are controlled and that contact ramps progressively, with no number for any of it. And what happens when LinkedIn challenges an action, which no page addresses. There is no help center to check, so on a client's account you would be finding out in production. The 5-euro extra account is the tell: at that price no proxy, browser profile or per-account infrastructure can be behind it.

CampaignStack answers those three questions in writing. A session cookie is consumed into an encrypted browser profile on our own server, behind one static residential proxy per account, and never stored in the database. Connection requests are capped at 3% of the account's connections per day under a weekly cap of 100 to 200, every action type has a daily budget below LinkedIn's limits, a new account starts at 10% of its cap and earns the rest through use, and sends are paced through business hours from a start time that moves daily. When LinkedIn challenges an action, that family of actions pauses on its own. The numbers are on the safety page, dated.

Sinky's AI is a suggestion layer: it proposes a reply in the inbox, ranks conversations, and writes a message from the thread's history. Who enters a sequence is decided by your database filters at sourcing time, and nothing later re-scores a lead against what you actually sell or watches them for a job change or a funding round. When the agency page offers to let the AI run conversations end to end, nothing between the model and the prospect reads the message first.

CampaignStack moves those choices into the system. Every lead is scored against every campaign's ICP and the score gates membership; signals update the score on a schedule; every AI draft passes a critic that reads the full brief and returns one objection before a person sees it; drafts that keep failing pin to the top of a review queue; and the whole platform, inbox and review queue included, is drivable over an MCP server with more than 300 tools. Sinky reaches other tools through Zapier, Make and an undocumented API. For a French solo operator the copilot may be the right amount of machine. For an agency whose name is on the account, the deciding and the checking are the product.