I spent 2 weeks reading 1-star reviews before writing a line of code. Here's what I found in the e-signature category.
I'm a solo iOS dev. Before building anything, I do this thing where I read every 1-star review of every app in a category I'm thinking about entering. For e-signature on iOS, the findings were wild enough that I built the app.
What the category actually looks like:
eSign App by Municorn — pulling significant monthly revenue (third-party estimates put it in the high six figures) with an app that, as of writing, is signature-only. No dates. No checkboxes. Users still pay.
Signature Scan by Profuse — also doing serious revenue, while its recent reviews are full of "blank output" and "charged after cancel" complaints.
DocuSign — has a widely-shared public review where a user was charged $7,777 after they thought they'd cancelled. Whether that was a billing edge case or a dark pattern, the review is real and the user wasn't alone.
Signeasy — was reported for downloading users' phone contacts. They've since walked it back, but the trust damage is in the reviews.
Apple's free Markup tool — confirmed bug where signatures placed on page 2+ silently disappear when you save.
So in 2026, the alternatives for "I just need to sign this PDF on my phone" are: pay scammy paid apps, sign up for an enterprise tool that might bill you incorrectly, or use a broken free tool from Apple. For a category with a $12B+ TAM. Solo dev opportunity, hiding in plain sight.
One thing nobody in the consumer space talks about:
Most "signed" PDFs from these apps are just images pasted on top of the document. Open the file in any desktop PDF editor, drag the signature off, send it back. There's no tamper-proofing, no audit trail, no way for the recipient to prove the document is real. That was the gap I actually wanted to close.
What I built:
eSign PDF — 100% on-device (no servers, no accounts), tamper-proof flattening with a SHA-256 verification certificate the recipient can run themselves, Vision AI that auto-detects signature/date/initial fields on any PDF, and transparent pricing ($4.99/wk with a 3-day trial, $29.99/yr, or $59.99 lifetime — localized per country). ESIGN & eIDAS compliant. Live in 12 App Store localizations on day one.
Three non-obvious lessons so far:
12-locale ASO matters more than I expected. Real installs from Brazil and other markets with zero ad spend there. Localizing metadata is one of the highest-leverage things a solo dev can do, and almost nobody bothers.
Apple Search Ads is meaningfully cheaper in Arabic markets than in the US. Same intent keywords, fraction of the CPI. If you're spinning up an ASA campaign and the US numbers look brutal, try Tier 2 markets first.
The "boring utility" framing is a feature, not a bug. Every time I'm tempted to add "AI chat with your PDF" or "AI contract summarization," I remind myself that the user has a document open right now and wants to sign it in 30 seconds. Anything that doesn't reduce time-to-signature is noise.
Now here's what I actually want to ask this community:
A lot of you on IH are solo devs, freelancers, or running small teams of 2-5 people. You're exactly the people who deal with the most contracts and NDAs, client agreements, contractor onboarding, equity letters, rental stuff for the co-working space, school forms for your kid in between everything else.
So a few honest questions:
What are you using right now to sign PDFs on your phone? Markup? DocuSign? Adobe? "I print it, sign it, and scan it back in like a savage"?
If you're paying for one of the bigger tools (DocuSign, Signeasy, SignNow, Adobe Acrobat), what made you stick with it, and what's the one thing that drives you nuts?
Would tamper-proof verification actually matter to you, or is it a "nice to have but I've never needed it" feature? Genuinely don't know — I built it because I thought it was important, but I want to hear if real indie founders care.
Counter-signature flow — I deliberately deferred this to v2 because adding it would mean a backend, an account system, and breaking the privacy story. Is that the wrong call? Would you pay more for a version that handles the "send to client, get it back signed" loop without uploading to a server?
I'm not running ads on this post, just genuinely trying to figure out where the v2 priorities should sit. If you've got 30 seconds to drop an answer in the comments, I owe you one.
App Store: https://apps.apple.com/us/app/esign-pdf-signature-maker/id6760910123
Marketing site: https://www.apptodesign.com/esign-pdf/
