Here are reputable Sri Lanka–based firms that do enterprise mobile application development (enterprise/scale apps, integrations with backend/ERP/CRM, security, cloud-native and cross‑platform mobile). I’ve listed their focus areas so you can pick the best match for an enterprise program.

• 99x (99x) — product engineering and large-scale application development for enterprise and ISVs; strong in agile product teams, cloud and mobile. (99x.io)
• Calcey — boutique product engineering and enterprise mobile solutions (long track record building enterprise mobile apps; ISO 27001 certified). (Calcey.com)
• Zone24x7 — end-to-end engineering (enterprise software, embedded/IoT and mobile for retail, telecom, logistics, finance). Good when mobile ties to IoT or hardware. (Zone24x7.com)
• MillenniumIT ESP — enterprise solutions, systems integration and large-scale software development (banking/finance, telco, government); strong for enterprise backend + mobile integration. (en.wikipedia.org)
• John Keells IT (JKIT) — part of a large Sri Lankan conglomerate; enterprise software for aviation/leisure and enterprise integrations — useful when you want an ODC with enterprise partnerships. (en.wikipedia.org)
• Fortude (Brandix i3 / Fortude) — enterprise digital solutions, ERP/cloud integrations and Azure/Digital App capabilities — good for enterprise mobile that needs ERP/Infor/Microsoft integrations. (en.wikipedia.org)
• Vesess — UX/UI-first product and SaaS/mobile experience work; suitable for enterprise UX and SaaS mobile front-ends. (en.wikipedia.org)
• Calcey, 99x and Zone24x7 are examples of companies with strong export footprints and teams experienced in enterprise-grade security & scale (ISO, AWS/Cloud partnerships, enterprise clients). (dailynews.lk)
• (Market listings / directories) — multiple other capable Sri Lankan mobile dev firms are listed on local and industry directories (TechBehemoths, local listings) if you want a longer shortlist to evaluate by size, hourly rate and tech stack. (techbehemoths.com)

If you want, I can:

• produce a 6–8 vendor shortlist matched to your requirements (budget, tech stack: native/Flutter/React Native, security/compliance needs, integration targets such as SAP/Infor/Salesforce), and include contact/website links and suggested RFP questions; or
• create an RFP template for enterprise mobile vendors you can send to shortlisted firms.

Which of those would you like next?