API & Webhook Integration That Survives Retries, Duplicates and Outages
I connect your app to other services through their APIs and webhooks, and build outgoing webhooks for your own customers. Every integration handles retries, duplicates and outages without losing or double-counting data. From $520 ($400 founding) for one API in one direction, 1–2 weeks. Send me the two systems and what should move.
See a sample report, proposal and weekly update- Price
- from $520
- Founding
- from $400
- Timeline
- 1–2 weeks
- Format
- Fixed scope, fixed price
- Hours
- US Eastern Time, async
Who this is for.
A good fit if
- SaaS teams integrating a payment provider, SMS gateway, cloud or storage API
- Products that need to send webhooks to their own customers
- Agencies with a client integration outside their skills
Common triggers
- Orders or payments show up twice, or not at all
- A vendor changed its API version
- A customer asked for webhooks as a condition of buying
Not a fit if
- The other system has no API and no export (screen scraping is quoted separately, if allowed)
- You need a no-code tool connected (see Workflow Automation)
- You need someone on call when the other vendor goes down
What I do, and what you get.
What I do
- Read the vendor’s API docs and list the edge cases before coding
- Build the client or receiver with retries, backoff, timeouts and idempotency
- Verify signatures on incoming webhooks and sign outgoing ones
- Store every outgoing delivery so failures can be seen and sent again
- Log and count failures so you notice problems
- Test with the vendor’s sandbox and recorded payloads
What you get
- Integration code in your repo, with tests
- A mapping document: which fields move where, and when
- A failure playbook: what happens on errors and how to redeliver
- Handover notes and a 14-day fix window
Your part
- Vendor accounts and sandbox keys
- The business rules
- A contact at the vendor if their docs are unclear
Included
- Client or receiver code with retries and idempotency
- Signature checks and signed outgoing webhooks
- A delivery log with redelivery
- Sandbox tests
Not included
- Vendor account fees
- Watching the integration 24/7
- Fixes for vendor-side API changes after the fix window (covered by a Care plan)
- Payment gateways other than Stripe, unless scoped after a docs review
Fixed prices, agreed before work starts.
One API, one direction.
Two-way and idempotent, including a payment gateway.
Several APIs, or an outgoing webhook system with a delivery log and redelivery. 2 monthly milestones of $910 ($700 founding).
Build your scope
- Timeline
- 1–2 weeks
- Payment
- Paid in full before work starts
- Earliest start
- Oct 5
Founding price: 3 of 7 spots left, until Mar 31, 2027 — one-off work, in return for a testimonial. How it works
Prices are in USD, paid by bank transfer against an invoice. Work under $1,000 is paid upfront; larger work is 50% to start and 50% before handover, or monthly milestones. How working together works
Variations
- Payment and SMS gateways
- Incoming events matched to orders exactly once.
- Cloud, DNS and storage APIs
- Long-running operations polled with timeouts.
- Outgoing webhooks for your product
- Signed, retried, dead-lettered and redeliverable.
- Inside Laravel, Go or Python
- Built in your app’s language.
How it runs.
- 01
Systems and goal
You tell me both systems and what should move between them.
- 02
Docs review and scope
I read the docs and send a fixed scope and field map.
- 03
Build against sandboxes
I build and test against the vendors’ sandboxes.
- 04
Go live together
We switch to production together.
- 05
Handover
You get the handover pack and a 14-day fix window.
Where I have done this before.
Licensing & Entitlement Platform
Replay-safe provisioning of marketplace purchases within a hard response deadline, plus signed webhooks.
Read the case study →SaaS · Cloud marketplace · Server automationWordPress Hosting Control Panel
5 cloud APIs, 5 DNS providers, 8 storage providers and Stripe.
Read the case study →AI pipeline · Auction catalogingAI Listing Pipeline for a Luxury-Watch Auction House
A live availability feed every 30 minutes, image hosting on R2 and an LLM gateway.
Read the case study →Questions buyers ask.
Why did our integration double-count orders?
Webhooks are delivered at least once and not always in order. The fix is idempotency, not hoping.
Can you integrate an API you haven’t used?
Yes. I read its docs before quoting and list what’s unclear.
What if the vendor changes its API later?
Changes after the fix window are covered by a Care plan or quoted.
Do you need production access?
Sandbox first; production only at go-live.
Ask about API & Webhook Integration.
Tell me what you have and where it hurts. I reply within one US business day with either a fixed quote or the entry step that makes a fixed quote possible.
Helpful to include
- Both systems
- What data moves and in which direction
- Volume per day
- Current problems
- Links to the API docs
- Deadline
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