You will get a custom API integration with OAuth, webhooks, and REST sync
Project details
Most integrations don't break in a loud, obvious way. They break quietly: a token that silently stops refreshing, a webhook that fires twice and double-charges someone, a sync that drifts a little more out of step every day until the numbers don't match. That's the part I build for.
I was the engineer behind the official Adobe Marketo Engage app on the Webflow Marketplace, and I worked on the official ActiveCampaign, Stripe, and PayPal apps too. That's OAuth 2.0, REST APIs against real third-party systems, token refresh, rate limiting, and webhook handling that has to survive production traffic and audits.
This service connects YOUR app to the services it depends on. I don't build marketplace apps for other platforms here.
Tell me which service, which direction the data moves, and what "in sync" means to you. I'll send progress at each milestone and hand off something documented that you can run yourself. If the scope shifts mid-build, I'll tell you what it costs before I touch it, not after.
I was the engineer behind the official Adobe Marketo Engage app on the Webflow Marketplace, and I worked on the official ActiveCampaign, Stripe, and PayPal apps too. That's OAuth 2.0, REST APIs against real third-party systems, token refresh, rate limiting, and webhook handling that has to survive production traffic and audits.
This service connects YOUR app to the services it depends on. I don't build marketplace apps for other platforms here.
Tell me which service, which direction the data moves, and what "in sync" means to you. I'll send progress at each milestone and hand off something documented that you can run yourself. If the scope shifts mid-build, I'll tell you what it costs before I touch it, not after.
Programming Languages
JavaScript, Python, TypeScriptCoding Expertise
Performance Optimization, SecurityWhat's included
| Service Tiers |
Starter
$1,200
|
Standard
$2,500
|
Advanced
$4,500
|
|---|---|---|---|
| Delivery Time | 7 days | 14 days | 24 days |
Number of Revisions | 2 | 3 | 4 |
Design Customization | |||
Content Upload | |||
Responsive Design | |||
Source Code |
Optional add-ons
You can add these on the next page.
Add an extra service to the integration
(+ 5 Days)
+$900
Event logging plus admin view
(+ 4 Days)
+$700
Extra field mapping
(+ 3 Days)
+$500Frequently asked questions
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PG
Penny G.
Aug 27, 2025
Webflow website addition
About Veldin
Senior Product Engineer | AI, API Integrations, Full-Stack SaaS
Sarajevo, Bosnia and Herzegovina - 2:25 am local time
The proof, public and clickable:
→ Led the Adobe Marketo Engage app and built the ActiveCampaign app — Marketo is Approved by Webflow and Enhanced-Security certified.
→ Contributed to the official Stripe and PayPal Webflow apps.
→ Built most of Webflow's integration for Slack's MCP launch — Webflow was one of 20+ launch partners alongside Atlassian, Canva, Linear, and Zoom.
I also ship complete products solo, from architecture to deployment:
→ Cloudless — an AI mobile app with a Claude-powered coach behind a secure serverless proxy (React Native)
→ Synqo — a multi-tenant workforce SaaS built solo (auth, scheduling, payroll, real-time dashboards)
→ Dora.ba — a live e-commerce + booking platform (260 products, 118 services)
What I'll build for you:
→ AI features — LLM integrations, AI agents, automation — in new or existing products
→ API & platform integrations — OAuth, webhooks, third-party APIs
→ Full SaaS builds — auth, billing, dashboards, multi-tenant
→ Web & mobile — Next.js, React, React Native
How I work: give me a clear scope and you get it shipped — fast, self-directed, fully async, with written updates at each milestone. No standups or daily syncs (a one-off scoping chat is fine). I'm newer to Upwork than to shipping — most of my work has been senior in-house and direct-client, and everything above is public and verifiable.
Stack: Next.js, React, React Native, Node.js, TypeScript, Python, Postgres/Supabase, Stripe, OAuth/webhooks, Claude/OpenAI.
Portfolio: veldin-portfolio.vercel.app
Steps for completing your project
After purchasing the project, send requirements so Veldin can start the project.
Delivery time starts when Veldin receives requirements from you.
Veldin works on your project following the steps below.
Revisions may occur after the delivery date.
Scope & access
You send the API docs and sandbox credentials. I confirm the data flow and what "in sync" means, in writing.
Build auth & sync
I build the OAuth and token-refresh and the data flow, with retries so nothing is silently dropped.