The verdict in three sentences
For a software vendor in Toronto, a public API with a developer portal requires an investment of EUR 15,000 to 50,000 (about USD 16,500 to 55,000) and 6 to 12 weeks of work. The API gateway costs EUR 0 to 800 a month depending on traffic and tooling. Well designed, it becomes a revenue line of its own and sharply reduces the custom development requests that clog your product team.
Pricing a public API in 2026
An API exposed to third parties has different requirements from an internal one. It must be stable, versioned, documented, secure and measurable. Here is the typical 2026 breakdown.
| Component | Content | 2026 range (EUR, excl. tax) | Duration |
|---|---|---|---|
| Design and OpenAPI contract | Resources, conventions, errors, pagination | 2,000 to 6,000 | 1 to 2 weeks |
| OAuth2 authentication and API keys | Client credentials, scopes, secret rotation | 2,500 to 7,000 | 1 to 2 weeks |
| Versioning and backward compatibility | v1/v2 strategy, deprecation, headers | 1,500 to 4,000 | 1 week |
| Quotas, rate limiting, billing | Plans, counters, overages | 2,500 to 8,000 | 1 to 2 weeks |
| Developer portal | Interactive docs, guides, sign-up, dashboard | 3,000 to 12,000 | 2 to 3 weeks |
| Sandbox and test data | Isolated environment, datasets | 1,500 to 5,000 | 1 week |
| Webhooks and SDKs | Signed events, JavaScript and Python SDKs | 2,000 to 8,000 | 1 to 2 weeks |
A first "integrator" version (20 to 30 endpoints, OAuth2, generated docs, sandbox) fits within EUR 15,000 to 22,000. A monetised API with paid plans, webhooks, SDKs and a white-label portal reaches EUR 35,000 to 50,000.
API gateway: which option and what monthly cost
The gateway centralises authentication, quotas and usage statistics. The choice depends on call volume and how much autonomy you want.
| Gateway | Model | Indicative 2026 monthly cost | Strengths | Limits |
|---|---|---|---|---|
| In-house middleware | Self-hosted | EUR 0 excluding servers | Full control | Maintenance is yours |
| Kong Gateway OSS | Self-hosted | EUR 50 to 200 infrastructure | Rich plugins, fast | DevOps skills required |
| AWS API Gateway | Pay per call | About USD 3.50 per million requests | Elastic, easy start | Variable bill, AWS lock-in |
| Managed Tyk or Gravitee | Subscription | EUR 300 to 800 | Built-in portal, analytics | Fixed cost from day one |
| Zuplo, Apigee | Subscription or contract | EUR 100 to several thousand | Native monetisation | Apigee oversized for an SMB |
For a vendor starting with fewer than 10 million calls a month, a self-hosted or pay-per-call gateway stays under EUR 150 a month.
Monetisation: what an API plan can earn
The API pays back in two ways: direct revenue through paid plans, and savings through fewer custom requests. B2B vendors in 2026 use pricing grids close to these.
| Plan | Indicative monthly price | Call quota | Target |
|---|---|---|---|
| Discovery | EUR 0 | 1,000 calls per day | Testing, small integrators |
| Standard | EUR 49 to 99 | 100,000 calls per month | SMB customers connecting their ERP |
| Pro | EUR 199 to 399 | 1 million calls, webhooks | Integrators, resellers |
| Enterprise | Contract, EUR 1,000 and up | Unlimited, 99.9% SLA | Large accounts |
| Overage | EUR 0.50 to 2 per 1,000 calls | Beyond quota | All paid plans |
Another often underestimated lever: a vendor receiving 8 to 15 custom development requests per quarter typically sees half of them disappear once the API is open, as customers build their own tooling.
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Mini case study
Ethan, CTO of a construction site management software vendor in Toronto, has 320 customers. He invests EUR 32,000 in an API with OAuth2, quotas and a portal, plus EUR 120 a month for the gateway. After 12 months, 45 customers subscribe to the Standard plan at EUR 79 and 8 integrators to the Pro plan at EUR 299, i.e. 3,555 + 2,392 = EUR 5,947 of monthly revenue, about EUR 71,000 a year. His team also saves 20 days of custom development per quarter, valued at EUR 550 a day, i.e. EUR 44,000 a year. Payback comes in under 4 months once usage ramps up.
FAQ
REST or GraphQL for a public API?
REST with an OpenAPI contract remains the standard expected by 80% of integrators in 2026. GraphQL makes sense if your customers have highly varied query needs, and costs 20 to 30% more to secure.
How much does documentation alone cost?
Docs generated from OpenAPI with Redoc or Scalar cost EUR 2,000 to 4,000. A full portal with guides, tutorials and per-language examples rises to EUR 8,000 to 12,000.
How do we stop a new version from breaking integrations?
Version in the URL or headers, keep the previous version for at least 12 months and announce deprecations 6 months ahead. Automated contract tests prevent 90% of regressions.
Does the API need to be privacy compliant?
Yes: limited scopes, access logging, data processing agreements with integrators and hosting in the right jurisdiction (PIPEDA in Canada, GDPR for EU customers). Budget EUR 1,500 to 3,000 for the legal and documentation work.
What maintenance should we plan after launch?
As a ballpark, 15 to 20% of the initial cost per year, i.e. EUR 3,000 to 10,000, for fixes, security and new resources.
Let's scope your project. Tell us which resources you want to expose, your integrator profiles and your monetisation goal, and we will price the API, the portal and the launch schedule. 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.
