TON Core: Report for 2025 H1

Report on the implementation of the TON Core roadmap for the first half of 2025.

https://telegra.ph/TON-Core---Report-for-2025-H1-08-03

Tolk 1.1 Programming Language

New in this release:

— Built-in maps (dictionaries);

— Enums;

— Private and readonly fields in structs;

— Overload resolution and partial specialization;

Next, the Tolk team will focus on automatic TypeScript wrapper generation for structs.

Read more »

IntelliJ TON 3.0.0

The biggest update yet. An impressive list of new features, improvements, and fixes. Every part of the plugin and every supported language has been improved.

The list of supported languages has grown:

TASM — the upcoming assembler standard for Tolk.

Fift assembly — now with enhanced support as part of Fift integration.

BoC files are no longer just opaque binaries — open them to view fully disassembled code!

This release also brings support for the latest Tolk 1.1.

Changelog (see for yourself) »

IntelliJ TON »

This year, we expanded the TON Core C++ node team:

🥷 Evgeny

Over 10 years of experience in blockchain development, including work on consensus and cryptography.

— First place in ICPC World Finals 2009 and 2012.

— Great results in other programming competitions, including Google Code Jam, Meta Hacker Cup and TopCoder Open.

🥷 Oleg

Distributed database engineer and researcher.

— Winner of the TON x CodeForces Contest.
— Bronze medal in the ICPC World Finals 2020.
— Top rating of Grandmaster on Codeforces
— Results in other programming competitions, including IEEExtreme, Google Hash Code, Microsoft BubbleCup Finals.

🥷 Vadim

Specializes in multithreading, working with databases and clusters.

— Winner of the TON Validation Contest and TON Smart Challenges.
— Second place in the Yandex Cup 2024 Backend.

🥷 Dan (20 y.o!)

MIT

— Winner of the TON Validation Contest.
— Gold medal in the International Olympiad in Informatics 2022.
— Gold medal in the Asia-Pacific Informatics Olympiad 2022.
— Gold medal in the Romanian Master of Informatics 2021.
— Gold medal in the International Autumn Tournament in Informatics 2021.

The TON Core team is working to enable transactions on the TON blockchain to be executed in less than 1 second — with no reduction in decentralization or scalability.

We have expanded the dev team and continue to implement the Optimization Roadmap that was published and partially completed earlier this year. Major L1 and API updates are ahead.

We plan to show the results in the TON main network as early as the first half of next year.

TON x Chainlink

The TON Core team was happy to help Chainlink integrate their product with TON.

Chainlink smart contracts are written in our new programming language, Tolk.

Meanwhile, we contributed to 3 more big upcoming releases — all starting or ending with “C.”

Node Update TON 2025.10, TON 2025.11

— Optimistic collation & validation: nodes can generate and verify block candidates before the previous block is fully finalized.

— New block compression algorithm.

— Enhanced overlays, peer discovery, and sync.

— Various improvements and fixes.

Full Changelog »

Blockchain configuration updated

The following improvements to the TON blockchain configuration were made by a network-wide vote of validators:

1. The parameter for launching BTC Teleport has been updated.

2. Updated system configuration smart contract code:

— Removed code related to an unused configuration key. Note that the configuration key itself was reset back in 2023.

— Added custom slot functionality that will be useful for stablecoins.

TVM 12

— Bounced messages can now include the full message body, error code, and additional data.

— New low-cost TVM instructions.

— Various improvements and fixes.

Full Changelog »

Tolk 1.2 Programming Language

— Rich bounced messages support (TVM 12).

— Cheaper smart-contract deployment thanks to new TVM 12 capabilities.

— Redefined address type.

— Improved compilation errors.

— Anonymous functions (lambdas).

— Borrow checker to catch undefined behavior.

Read more »

Node Update TON 2025.12

CellDB 2.0 and the Fast State Serializer are now enabled by default.

The validator engine gains parallelism, network traffic compression is improved, along with various fixes and enhancements.

Full Changelog »

The R&D phase has been completed — research and development of the task of speed up operations in the TON blockchain to less than 1 second while maintaining scalability, security, and decentralization.

During the work, three key areas were identified that, taken together, will allow the desired result to be achieved.

1. L1 and Node improvements

1.1. New Catchain 2.0 consensus

The current Catchain + BCP consensus stack has been replaced with a new protocol — Catchain 2.0, based on Simplex / Alpenglow algorithms adapted to the TON architecture.

The consensus protocol determines how validators share data, verify and accept blocks with transactions.

Simplex and Alpenglow are modern open consensus protocols that are characterized by high speed and relative simplicity.

Catchain 2.0 allows blocks to be finalized in 200–400 milliseconds while maintaining the same level of security. Previously, the block finalization time was about 2.5 seconds.

An additional advantage in terms of security is the widespread knowledge of these protocols, which greatly simplifies their audit.

1.2. New block broadcast protocol — "two-step" broadcast

Blocks are transferred between network nodes using the broadcast protocol. We have redesigned this network protocol, reducing the block delivery delay from approximately 700 ms to ~100 ms.

1.3. Additional optimizations

A number of additional optimizations have also been made to the C++ implementation of the TON node, including:

— block compression during transmission;

— parallelization of validation;

— the ability to exchange data between validators not only via the RLDP2 protocol, but also via TCP or QUIC. Based on the test results, it may be possible to switch to one of these protocols.

In addition to the main solutions, the internal statistics system was refined, as well as the internal tools for benchmarks and measurements for nodes, validators, and API.

2. API

2.1. Reduced API latency

The Toncenter API has been optimized, resulting in a latency of 30–100 milliseconds for obtaining the status of an operation via the Streaming API V2.

2.2. New functionality

Streaming API V2 in Toncenter now returns two statuses of operation instead of one:

confirmed — the block has appeared in the shardchain;

finalized — the block has been accepted into the masterchain.

Previously, only the finalized status was supported.

3. UX

A new UX approach has been proposed. Since an operation with the confirmed status has a rollback probability of less than 1%, applications can display it to the user at this stage. The user can then immediately perform the following operations without waiting for finalization.

At the finalized stage, the application can additionally mark in the UI that the operation is completely finalized.

This is similar to the confirmation model in other blockchains, where the operation is displayed after being included in the first block, and final finalization occurs after several block confirmations — at the same time, the user can immediately continue interacting with the blockchain.

This is a solid addition to last year's UX and kernel updates.

All of the above components have been completed separately. Component integration is underway, followed by testing on the TON test network.

Progress of Sub-Second update deployment on the TON mainnet

TON is gradually transitioning to an architecture where operation times are measured in milliseconds rather than seconds.

The Sub-Second update is one of the biggest technological improvements to the network in recent years.

New API and UX already on the main network

— Toncenter API has released a new accelerated Streaming API V2 for all users on the main and test networks.

— The first products — MyTonWallet and tonscan.org — have already switched to Streaming API V2 on the main and test networks.

This has already nearly halved the operation time in these products, even though the blockchain itself is still operating in the same mode.

— Other products and services in the ecosystem can already connect to the new API and implement the updated UX approaches.

Blockchain update

— On February 12, the main network validators were updated to the new accelerated network layer code and Catchain 2.0 consensus.

— The new functionality has not yet been enabled and will be activated after testing is complete.

Progress of Sub-Second update testing on the test network

The TON test network has been running stably for over a month since the January 23 update with the activation of Sub-Second mode:

— On average, 2-3 blocks are created per second.

— The network is operating under real organic load.

— Various validators are participating.

Load testing

During testing, tests were conducted under relatively high load. The results showed that with 1,000 transactions per second in a single shardchain, the operation time remains less than a second.

For comparison, even during periods of high load on the main network during the minting of Notcoin, DOGS, and Hamster Kombat projects, the average TPS did not exceed ~500.

Improvements and fixes

During testing, the TON Core team made a number of improvements. Of particular note:

— Disk performance has been optimized so that nodes with slower disks can synchronize stably at the new block rate.

— The stability and performance of the new consensus has been improved, and the handling of scenarios where some validators are temporarily out of service has been improved.

In addition to working on Sub-Second, two service updates have been released with fixes and improvements to the stability of the main network: TON 2026.02 (February 12) and TON 2026.02-1 (February 24).

Tolk Programming Langauge 1.3

— Type array<T> — dynamically sized arrays backed by TVM tuples.

— Type unknown — a TVM primitive with unknown contents.

— Type lisp_list<T> — nested two-element tuples (FunC-style).

— Type string — text chunks backed by snaked cells, with StringBuilder for concatenation.

— Compile-time string methods: "str".crc32(), "str".sha256(), etc.

— Null coalescing operator — ?? like in TypeScript.

— Import path mappings — import "@third_party/utils".

— Compile-time reflection via @stdlib/reflection.

— Custom serializers now support structures and generics.

— The compiler now reports multiple errors at once.

— Focused on stability — fixed dozens of minor issues found by LLM fuzzing.

— Extensive internal refactoring towards being stateless and multi-threaded.

Release »

Read more »

Sub-Second mainnet activation starts

The public bug bounty contest for the TON Sub-Second update has been completed.

We thank all participants for their work and valuable feedback. The corresponding changes have already been applied to the codebase. No major consensus changes were required.

The final contest results and reward distribution will be announced later.

This contest was the final stage of testing before mainnet activation. Prior to that, the update had already passed internal testing by TON Core and extended testing in testnet.

We are now starting the activation of the Sub-Second update in TON mainnet.

For additional reliability, activation will be performed in 3 stages:

Update plan:

March 31 (today): Upgrade validator nodes to the version supporting the latest consensus changes.

April 2: Vote to activate the new consensus on the basechain and enable a moderate block rate increase.

April 7: Vote to fully activate fast consensus on both the basechain and masterchain and then upgrade validator nodes.

The Sub-Second update is a major protocol upgrade comprising a substantial number of changes.

Despite comprehensive testing, validators are advised to maintain heightened operational readiness during the next two weeks, from March 31 to April 12.

The TON Core team will remain available throughout the deployment and is prepared to respond promptly to any situations.

Sub-Second for the TON Ecosystem

As part of the Sub-Second mainnet rollout, ecosystem participants should review the following guidance.

For Validators and Node owners

Follow @tonstatus.

For API developers

Please update your own nodes as described in the corresponding post.

APIs will continue functioning after the network upgrade. No additional compatibility changes are required.

If you were previously using low-end hardware, you may need to upgrade it due to the increased block rate

To deliver near-instant UX, we recommend adopting the latest API practices:

— Enable WebSockets support.
— Optimize general API latency.
— Support Pending and Confirmed operation statuses.

You can refer to the changes in the Toncenter API.

For exchanges and payment services

If you are running your own node, please update it as described in the corresponding post.
If you are using an API, whether external or self-hosted, no action is required.

No additional changes are needed. Transaction finality should continue to be determined based on masterchain finalization, as before.

For products and dApps

If you are running your own node, please update it as described in the corresponding post.
If you are using an API, whether external or self-hosted, no action is required.

Products and APIs will continue functioning after the network upgrade. No additional compatibility changes are required.

To deliver near-instant UX, we recommend adopting the latest UX practices:
— Use Toncenter Streaming API V2.
— Display an operation in the UI once it reaches Pending status.
— Mark an operation as completed once it reaches Confirmed status.

You can refer to the changes in mytonwallet.io and tonscan.org.