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Instantly vs Reply.io: We Tested Both and Neither Won Clean

Ibby SyedIbby Syed, Founder, Cotera
9 min readMarch 7, 2026

Instantly vs Reply.io: We Tested Both and Neither Won Clean

Instantly vs Reply.io: We Tested Both and Neither Won Clean

Priya wanted multichannel. She'd been running email-only campaigns on Instantly for five months and was getting solid results, 3.6% reply rate across 14 campaigns, but she kept hearing that adding LinkedIn touches would push reply rates above 5%. Reply.io promised exactly that: email sequences with LinkedIn connection requests, profile views, and InMail baked into the same workflow.

So she ran both. Instantly for email-only campaigns. Reply.io for multichannel sequences that combined email with LinkedIn. Same ICPs, same value props, same team. Ninety days.

The result was messier than she expected.

What Each Platform Actually Does

Instantly is an email sending platform. That's it, and that's the point. You connect sending accounts, warm them up, load leads, write sequences, and send. The product is focused, fast, and priced for volume. Unlimited sending accounts on paid plans. Native warmup. Clean UI. If all you want to do is send cold email at scale, Instantly does it well and doesn't try to do anything else.

Reply.io is a multichannel outreach platform. Email, LinkedIn automation, phone tasks, WhatsApp, SMS. You build sequences that mix channels, so step one might be a LinkedIn connection request, step two an email, step three a profile view, step four a follow-up email, step five a phone task. The idea is that touching a prospect across multiple channels increases the chance they respond.

The philosophical difference matters. Instantly assumes email is enough if you do it well. Reply.io assumes email alone isn't enough and you need to surround the prospect. Both positions have evidence behind them. Neither is universally true.

The Test Setup

Priya split 1,200 leads into two equal groups. Demographics matched: VP and Director level at B2B software companies, 100-500 employees, US and UK.

On Instantly, she ran a four-email sequence over 14 days. Subject line, short body, clear CTA. The sequence she'd been refining for months.

On Reply.io, she built a seven-step multichannel sequence over 21 days. Step one: LinkedIn connection request with a short note. Step two (day 2): email if they accepted, different email if they didn't. Step three (day 5): LinkedIn profile view. Step four (day 7): follow-up email. Step five (day 10): another LinkedIn touch. Step six (day 14): email. Step seven (day 21): final email with a breakup angle.

Setup time told the first story. Priya had the Instantly campaign live in about 40 minutes. The Reply.io sequence took her most of an afternoon, roughly four hours. Configuring LinkedIn automation, setting up conditional branches based on connection acceptance, writing channel-specific copy for seven steps instead of four. The complexity was real.

Reply Rates

Instantly: 3.4% reply rate. Twenty replies from 600 leads.

Reply.io: 4.7% reply rate. Twenty-eight replies from 600 leads.

Eight additional replies. Priya was initially excited about the 38% improvement in reply rate. Then she looked at where those replies came from.

Of Reply.io's 28 replies, 19 came from email steps. Nine came from LinkedIn. The email-only reply rate within Reply.io was 3.2%, which was actually lower than Instantly's 3.4%. The LinkedIn channel added incremental replies, but it didn't improve email performance. If anything, the longer sequence with LinkedIn gaps between emails may have reduced email urgency.

The nine LinkedIn replies broke down further. Four were genuine interest. Three were polite "thanks for connecting, not interested right now." Two were "please stop messaging me on LinkedIn." So the LinkedIn channel produced four qualified replies out of 600 leads. That's a 0.67% incremental qualified reply rate.

Tomás looked at the numbers and said: "So LinkedIn added four real conversations. Was it worth the extra setup time and the higher platform cost?"

Cost Per Reply

Instantly's Growth plan at $30/month. Reply.io's comparable plan at $59/month per user. For our test volume, Instantly cost about $77/month total, Reply.io cost about $166/month.

Cost per reply on Instantly: $3.85. Cost per reply on Reply.io: $5.93. Cost per qualified reply: $5.13 on Instantly (15 of 20 were qualified), $6.64 on Reply.io (25 of 28 were qualified, though the LinkedIn ones were borderline).

Instantly was cheaper per reply. Reply.io generated more replies but at a higher unit cost. If you're optimizing for total pipeline and budget isn't tight, Reply.io's higher volume wins. If you're optimizing for efficiency, Instantly's lower cost per reply wins.

Neither answer is wrong. It depends on whether your constraint is budget or pipeline.

The LinkedIn Problem

Here's what Priya didn't expect: LinkedIn automation created friction with prospects in ways that email didn't.

Three people mentioned during sales calls that they'd noticed the automated LinkedIn connection request. One said: "I could tell it was automated because I got the connection request and then an email with the same pitch two days later. It felt choreographed." Another said: "I don't love when vendors automate LinkedIn. It feels like you're in my personal space."

These are anecdotes, not data. But they point to a real tension. LinkedIn is perceived as more personal than email. When outreach on LinkedIn feels automated, the negative reaction can be stronger than it would be for an automated email, because nobody expects cold email to be handcrafted but people do expect LinkedIn messages to be personal.

Priya adjusted her Reply.io sequences after the test. She removed the automated connection requests and replaced them with manual LinkedIn tasks, reminders for her SDRs to send personalized connection requests by hand. This improved the quality of LinkedIn interactions but also increased the time cost per prospect.

Where Neither Platform Helps

Both Instantly and Reply.io give you campaign-level metrics. Open rates, reply rates, bounce rates, click rates. Reply.io adds LinkedIn-specific metrics like connection acceptance rate and InMail response rate.

What neither platform does is think about those metrics.

After 90 days, Priya had data from 14 Instantly campaigns and 8 Reply.io sequences. She could see that Campaign 7 had a 5.1% reply rate and Campaign 12 had a 1.9% reply rate. But why? Was it the ICP? The copy? The sending time? The lead source? To answer those questions, she had to export data, build spreadsheets, and spend hours looking for patterns.

She found one interesting pattern buried in the data: leads sourced from Apollo with the "recently changed jobs" filter replied at 2.4x the rate of leads without that filter. Across both platforms. That single insight, applied to future campaigns, improved her overall reply rate by about 0.8 percentage points. But it took her a full day of analysis to find it.

We pointed an Apollo cold outreach agent at the same data and it surfaced similar patterns in minutes instead of hours. The agent looks at lead source, persona, industry, sequence length, and sending patterns across all campaigns and identifies what's working and what isn't. It doesn't care whether the campaigns ran on Instantly or Reply.io. It cares about which variables correlate with replies.

That kind of cross-campaign intelligence is what actually moves reply rates. The platform sends the emails. The agent figures out which emails are worth sending.

The Verdict That Isn't a Verdict

If Priya had to pick one platform today, she'd pick Instantly for most campaigns and layer LinkedIn outreach manually on top for high-value prospects. The cost savings from Instantly fund the time the team spends on personalized LinkedIn touches for the accounts that matter most.

Reply.io is the better product if you genuinely need multichannel automation at scale. If you have an SDR team of five or more, if you're doing outbound across email, LinkedIn, and phone simultaneously, if you need everything in one workflow. The platform handles complexity well once it's set up.

But "once it's set up" is doing a lot of work in that sentence. The setup complexity is real. The maintenance complexity is real. Conditional branching across channels creates sequences that are hard to debug when something underperforms. When your seven-step multichannel sequence gets a 1.8% reply rate, figuring out which of the seven steps is the problem, and on which channel, is genuinely difficult.

Instantly's simplicity is a feature, not a limitation. When a four-step email sequence underperforms, you know it's the emails. Change the subject line, tweak the CTA, adjust the timing. The feedback loop is tight.

The multichannel question isn't really about platforms. It's about whether adding channels adds enough value to justify the added complexity. For Priya's team, the answer was "sometimes, for specific accounts, when done manually." That's not the answer Reply.io's marketing page would give you, but it's the answer the data gave us.

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