Head-to-head
Cometly vs Fospha
Both promise clearer numbers than Meta and Google report, and both replace the pixel-only view most operators start with. But they answer different questions. One traces each paid conversion to real Stripe revenue and pushes that back to the ad platforms. The other models where a whole brand's revenue comes from without firing a pixel.
By Marcus Flynn, tracking and attribution editor. Updated 28 September 2026.
Pick Cometly if you sell on Stripe and want deterministic attribution that ties each paid conversion to the ad that drove it and feeds those conversions back to Meta and Google; pick Fospha if you are a retail brand spending six figures a month that wants pixel-free modeled measurement of your whole channel mix and marketplaces, run for you.
Quick answer
Cometly is our top pick for most people. Cometly is a real, established attribution platform, and its server-side Conversion API is genuinely good at the job it claims. The catch is fit. In 2026 Cometly is built for B2B SaaS: it ties ad spend to Stripe revenue and CRM pipeline, right through to closed-won ARR. If that is your business, it is worth a demo. If you are a DTC or affiliate media buyer, note that Cometly has moved away from the ecommerce market it once served, it no longer publishes prices or runs a free trial, and you are quoted on a call. You will regret buying it if you expected a route-through campaign tracker, if you run cash-on-delivery or email-less checkouts, or if you need to see a price and test against your own numbers before you talk to sales.
- Cometly. Best for B2B SaaS teams tying ad spend to Stripe revenue and CRM pipeline.
- Fospha. Best for Retail and ecommerce brands spending six figures a month that want modeled measurement instead of pixels. From $1,500/mo.
Side by side
| Tool | Server‑side CAPI | Anti‑fraud kit | Self‑hosted | From |
|---|---|---|---|---|
| 11. Cometly | –Unknown | –Unknown | –Unknown | Not listed |
| 13. Fospha | –Unknown | –Unknown | –Unknown | $1,500/mo |
Cometly: pros and cons
What works
- Server-side Conversion API is the genuine strength. Cometly sends deduplicated conversions back to Meta, Google, LinkedIn and TikTok, and reports Meta event match quality up to 9.3 out of 10 where a manual setup sits at 4 to 5. Buyers on r/FacebookAds confirm it pushed more matched data to Meta than other trackers they had run.
- Revenue attribution built around Stripe and the CRM, not just clicks. The native Stripe sync ties trials, new customers, recurring revenue and LTV to the originating ad, and HubSpot and Salesforce lifecycle stages map onto the same touchpoints, right through to closed-won ARR. That is the report a SaaS finance team will actually defend.
- Modern data plumbing under it. A cookieless Comet Pixel with cross-device identity, 70-plus native integrations, an Agent you query in plain English instead of writing SQL, and on Enterprise a warehouse sync to Snowflake or BigQuery plus an MCP server that lets an AI agent read your attribution data. The vendor puts setup at hours rather than weeks.
- Established and reviewed, not a new app. Comet LLC has tracked paid spend for years, with named case studies (ClickFunnels reports a 31% ad-return lift, Trainual a 40% improvement in 90 days) and aggregate ratings of 4.8 out of 5 on G2 across 36 reviews and 3.6 out of 5 on Trustpilot across 92.
What to watch
- It is not a route-through campaign tracker. Cometly attributes traffic to your own site and funnel; it does not rotate offers, split traffic across landers by rule, or distribute clicks the way Voluum, RedTrack or Binom do. That matters most to affiliate media buyers running many offers through a redirect. A SaaS team sending paid traffic to one funnel does not need routing.
- It has left the DTC and ecommerce market it once served. Cometly's own site now names Triple Whale as the ecommerce tool and positions itself for B2B SaaS. Shopify still integrates, but reviewers report weaker matching on cash-on-delivery and email-less orders, so an ecom brand should demand proof on its own orders before buying.
- No public price and no free trial. Every plan is usage-based on monthly pageviews and quoted on a sales call, and Cometly says it does not run a trial because attribution needs setup first. Buyers who want to test against their own numbers before paying, or just want a price before a call, get neither. One G2 reviewer wanted more transparent negotiation and flagged pricing changes over time.
- Support and journey timing draw the recurring complaints. The long-running r/FacebookAds thread reports support replies measured in business days and trouble seeing the full pre-purchase journey or getting purchases captured fast enough. The sample is small, but it is consistent enough that you should test response times and event latency during onboarding.
Fospha: pros and cons
What works
- Non-pixel measurement that credits the upper-funnel channels last-click misses. Because it models from 100% of your real store revenue rather than platform-reported conversions, it surfaces contribution from prospecting social, YouTube, TikTok and display that GA4 and in-platform ROAS tend to undercount.
- Well reviewed by the brands that use it: 4.5 out of 5 from 51 G2 reviews, with recurring praise for ease of use, support and finally seeing channel value that click tracking hid.
- Measures marketplaces, not just your own site. On Pro and up it models the halo from paid media into Amazon and TikTok Shop sales, which pixel-based DTC dashboards structurally cannot see.
- Daily outputs with forecasting, not a quarterly report. The model retrains daily and Beam projects returns at different spend levels, so it works as a budget-allocation tool and not just a scorecard.
- Fast, transparent onboarding: most clients are live in under 28 days with 24 months of historical data, and Fospha runs a glass-box model you can interrogate layer by layer rather than a black box.
What to watch
- No free trial and no self-serve sign-up. You book a demo and commit to paid onboarding before you see it work on your own data, so the only way to validate it is to buy it. Ask for two or three references from brands like yours before you do.
- The floor is high: Lite is $1,500 a month and is built for brands already spending $100k to $500k a month on media. Below roughly $100k a month of spend it is overkill, and its own pricing tiers say so.
- Pro adds a percentage of your media spend on top of a $2,000 base, and Fospha does not publish that percentage, so the true all-in cost is opaque until you talk to sales.
- It reports modeled estimates, not deterministic user-level tracking, so its numbers will not match Meta, GA4 or Shopify. That is the point of a mix model, but it means your team needs a governance rule for which source to trust, and Fospha itself says the ad-level view is directional, not creative-level truth.
- Reporting flexibility is a common gripe: G2 reviewers mention limited report editing, filtering and segmentation friction, and manual data work to get some cuts of the data. It is a measurement layer, not a build-your-own BI tool.
The real differences
What each one actually is
Cometly is a marketing attribution platform, and in 2026 it is built for businesses that sell on Stripe. It stamps every click with a cookieless pixel, stitches the visitor to their eventual Stripe conversion, and then feeds that conversion back to the ad platforms. Its own site puts it plainly: Stripe knows who pays. Ad platforms only know who clicks. Cometly stitches the two together, so every trial, paid conversion, and renewal flows back to the ad, audience, and creative that drove it. On top of that sit HubSpot and Salesforce lifecycle stages, so a report can run from ad spend all the way to closed-won ARR. Read the full Cometly review for the setup detail.
Fospha is not a tracker at all. It is a managed measurement layer that credits every channel from your store's real revenue, without pixels. In its words, it moved away from pixel-based tracking early, rebuilding measurement from the ground up to give every channel, including the ones that generate demand, the credit it deserves. A daily marketing mix model reads your revenue, your ad spend across every platform, and 24 months of history, then estimates what each channel actually contributed. The Fospha review covers who runs it and at what spend.
Deterministic revenue against a modeled channel mix
This is the whole decision. Cometly is deterministic where it can be: it links a specific paid click to a specific Stripe customer, so you can point at one conversion and name the ad, the audience and the creative behind it. Fospha never claims to do that. It reports modeled estimates at the channel level, telling you that prospecting social or YouTube drove a share of last month's revenue that last-click missed, but not which click bought what.
If your question is "which creative is producing paying customers, and how do I feed that back to Meta," Cometly answers it directly. If your question is "across my whole media mix, where is the money really coming from and how should I split next month's budget," Fospha answers that one, and it answers it at a level a single-funnel tracker cannot reach.
What happens to your conversions
For a paid-traffic operator, the sharpest difference is what each tool does with a conversion after it records one. Cometly sends it back. Its server-side Conversion API pushes deduplicated conversions to Meta, Google, LinkedIn and TikTok, and it reports Meta event match quality up to 9.3 out of 10 where a hand-built pixel often sits at 4 to 5. That returned data is what trains the ad platform's bidding, and it is the core reason a media buyer who owns their checkout buys an attribution tool at all.
Fospha sends nothing back. It is a measurement layer, not a conversion pipe: it tells you where revenue came from, but it does not push events to any ad platform's API to improve targeting. That is by design, not a bug. It just means Fospha cannot close the feedback loop, and if that loop is the point for you, it is not the tool for the job.
What Fospha sees that Cometly cannot
The trade runs the other way too. Because Fospha models from 100% of your store revenue rather than platform-reported conversions, it surfaces the upper-funnel channels a click model structurally undercounts: prospecting social, YouTube, TikTok and display that plant demand days before the converting click. On its Pro tier and up it also models the halo from paid media into Amazon and TikTok Shop, revenue that never touches your own checkout and that Cometly, which lives on your site and your Stripe account, cannot see.
For a brand whose growth depends on prospecting and marketplaces, that reach is worth more than any single-click precision. For an operator running paid traffic straight to a funnel they own, it mostly is not.
Why the numbers will not line up
Neither tool will match Meta, GA4 or Shopify, and they will not match each other. Cometly reports deterministic conversions it can stitch to Stripe, so its total is grounded but can miss touches it never identified. Fospha reports modeled estimates, so its channel totals move as the model retrains daily and will never reconcile cell for cell with a platform dashboard. If you ran both, you would get two different, internally consistent answers. Pick the one whose method matches the decision you actually make, and set a governance rule for which source your team trusts.
The fit question, and what neither one is
Cometly has pivoted hard to B2B SaaS and, by its own positioning, left the DTC and ecommerce market it once served; it now names Triple Whale as the ecommerce tool. If you sell subscriptions or one-time offers on Stripe, that is exactly the lane it is built for. If you are a pure ecom brand with cash-on-delivery or email-less orders, demand proof on your own orders first, and weigh Fospha or Triple Whale instead. Cometly also publishes no price and runs no free trial, so you are quoted on a call before you can test it. That is real friction, and for a buyer who wants to see a number and validate against their own data first, it is a reason to hesitate.
One thing to be clear about: neither of these is a route-through campaign tracker. If you run many offers through a redirect and need to rotate landers and split traffic by rule, look at a dedicated tracker such as RedTrack or the picks on the best-of roundup, not at either of these. If you have already decided against a click tracker and are weighing Fospha against one, ClickFlare vs Fospha lays out that fork; RedTrack vs Cometly does the same for Cometly.
What the reviews say
Both are established and reviewed, not new apps. Cometly rates 4.8 out of 5 across 36 G2 reviews and 3.6 out of 5 across 92 on Trustpilot, with named case studies and consistent praise for how much matched data its Conversion API pushes to Meta; the recurring complaints are support replies measured in business days and trouble seeing the full pre-purchase journey. Fospha rates 4.5 out of 5 across 51 G2 reviews, praised for ease of use and for finally showing channel value that click tracking hid, with limited report editing and filtering as the common gripe. Both samples are modest, so treat the pattern as a signal, not a verdict, and test your own case during onboarding.
Changelog
28 September 2026. First published. Prices and positioning read from each vendor's own site on 27 September 2026. We will revisit within 90 days.
What each one costs
Cometly publishes no price. Every plan is usage-based on monthly pageviews and quoted on a sales call, and Cometly says it does not run a free trial because attribution needs setup before it means anything. Buyers who want a number before a call, or who want to test against their own conversions first, get neither. One G2 reviewer asked for more transparent negotiation and flagged pricing changes over time. Budget for a demo and a scoping call, not a card-on-file sign-up.
Fospha starts at $1,500 a month for its Lite tier, built for brands already spending $100,000 to $500,000 a month on media. Pro adds ad-level reporting plus Amazon and TikTok Shop modeling from a $2,000 base, with an undisclosed percentage of your media spend on top, so the all-in cost is opaque until you talk to sales. Enterprise is quoted. There is no free trial and no self-serve tier: you book a demo and commit to paid onboarding, which most clients complete in under 28 days with 24 months of historical data loaded. Fospha describes its lineup as three tiers, from measurement foundation to full enterprise setup.
Prices read from each vendor's own pricing page, current as of 27 September 2026.
Our pick
Cometly
Cometly is a real, established attribution platform, and its server-side Conversion API is genuinely good at the job it claims. The catch is fit. In 2026 Cometly is built for B2B SaaS: it ties ad spend to Stripe revenue and CRM pipeline, right through to closed-won ARR. If that is your business, it is worth a demo. If you are a DTC or affiliate media buyer, note that Cometly has moved away from the ecommerce market it once served, it no longer publishes prices or runs a free trial, and you are quoted on a call. You will regret buying it if you expected a route-through campaign tracker, if you run cash-on-delivery or email-less checkouts, or if you need to see a price and test against your own numbers before you talk to sales.
Frequently asked questions
Cometly or Fospha: which should I pick?
Does Fospha send conversions back to Meta and Google like Cometly does?
Which is cheaper to start with?
Can Cometly measure Amazon or TikTok Shop sales the way Fospha does?
Do I need either one to run paid traffic?
Sources
Other sources
4 discussions and reviews read for this page. Quotes are excerpts; open a link to read the original in context.
- [cometly-home] Cometly | Marketing Attribution Software
- [cometly-stripe] Cometly | Marketing Attribution Software
- [fospha-home] Fospha | The Measurement Operating System for Retail Commerce
- [fospha-price] Fospha pricing
How we compared these
We do not run paid campaigns through either tool. We read each vendor's own documentation and pricing, verify every number against the source, and weigh the long-term reports of operators who run them at real spend. The full rubric is on the methodology page.