The verdict in three sentences
A custom public API for your partners runs between 35,000 and 80,000 USD in Singapore in 2026, design and build included. Expect 2 to 4 months and 500 to 1,000 USD/month of maintenance for security, versioning and developer support. A well-designed API becomes a revenue channel through usage-tier monetisation and locks partners into your product.
What makes up a public API's price
Exposing an API externally takes far more than an endpoint. You need key-based authentication (or OAuth), quotas and rate limiting, interactive OpenAPI documentation, a developer portal, versioning and fine-grained observability. Price depends on the number of endpoints, the security level and monetisation needs.
| Scope | Contents | 2026 price (USD) | Timeline |
|---|---|---|---|
| Essential API | 5-10 endpoints, API key, OpenAPI doc | 35,000 - 45,000 | 2 mo |
| Standard API | + Quotas, dev portal, versioning | 48,000 - 62,000 | 3 mo |
| Advanced API | + OAuth, monetisation, sandbox | 65,000 - 80,000 | 4 mo |
| Premium partner API | + SLA, webhooks, client SDK | 80,000 - 120,000 | 4-6 mo |
| Custom dev portal | Console, keys, billing | +12,000 - 28,000 | +4-6 wks |
A senior backend/API developer's day rate in Singapore ranges from 700 to 1,200 USD in 2026. A standard API represents 45 to 65 person-days including load and security testing.
Monetising by usage tiers
The most common model is based on call-volume tiers. It turns the API into a profit centre while staying clear for partners.
| Tier | Calls/month included | 2026 indicative price | Overage |
|---|---|---|---|
| Free / Sandbox | 1,000 | 0 USD | Blocked |
| Starter | 50,000 | 55 USD/month | 0.90 USD/1,000 calls |
| Business | 500,000 | 279 USD/month | 0.55 USD/1,000 calls |
| Scale | 5,000,000 | 999 USD/month | 0.35 USD/1,000 calls |
| Enterprise | Custom quote | Contract + SLA | Negotiated |
Mini case study
Julien, CTO of a SaaS vendor in Singapore (logistics software), wanted to open an API to 30 enterprise clients demanding integrations. Each ad-hoc integration cost him 4 to 6 dev days, roughly 5 per quarter.
He invested 48,000 USD in a standard API delivered in 3 months, with a developer portal and tier-based monetisation. Result: ad-hoc integrations disappear (5 x 5 days/quarter x 800 USD day rate = 20,000 USD/quarter saved), and 12 partners subscribe to the Business tier at 279 USD/month, i.e. ~40,000 USD/year of additional recurring revenue. The API pays for itself in the first year, including maintenance at 600 USD/month.
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FAQ
Is a public API the same price as an internal one?
No. A public API requires security, quotas, documentation and developer support. It typically costs 40 to 70% more than an internal API for the same functional scope.
Do we always need OAuth?
Not always. API-key authentication is enough for many B2B scenarios. OAuth is justified when end users authorise access to their own data.
Is documentation included?
Yes. Interactive OpenAPI docs are part of the build; they are essential to adoption. A full developer portal is optional from 12,000 USD.
How do we set tier prices?
We start from your marginal cost per call and the value to the partner. Tiers should keep a generous free tier for trials and a growing net margin on paid tiers.
Who owns the API?
The code and OpenAPI schema are yours. You control your tiers, keys and billing with no third-party dependency.
Let's scope your project. Describe your target endpoints, partner count and monetisation model, and we will scope an API between 35,000 and 80,000 USD. Detailed quote within 48 h. WhatsApp +221 77 596 93 33.
Mohamed Bah
Fondateur, Kolonell
Passionate about digital and entrepreneurship in Africa, Mohamed has been helping Sénégalese businesses with their digital transformation since 2020. Founder of Kolonell, he believes every SME deserves a professional and accessible online présence.
